Thiopental Panpharma (Thiopental Sodium 0.5 g)
Ultra-short-acting barbiturate — powder for solution for intravenous injection — hospital-only prescription
Quick Facts About Thiopental Panpharma
Key Takeaways About Thiopental Panpharma
- Rapid induction agent: Thiopental produces unconsciousness within 30 to 60 seconds of intravenous injection and lasts approximately 5 to 10 minutes from a single dose due to redistribution.
- Hospital-only medication: Administration must be performed by, or under the direct supervision of, an anesthesiologist with full resuscitation facilities immediately available.
- Absolute contraindication in porphyria: Thiopental must never be used in patients with acute intermittent porphyria, variegate porphyria or hereditary coproporphyria, as it can precipitate fatal porphyric crises.
- Cardiorespiratory depression: Expect dose-dependent apnea, hypotension and reduced cardiac output; continuous monitoring of airway, breathing and circulation is mandatory throughout administration.
- Alkaline solution - incompatibility risk: Reconstituted thiopental (pH approximately 10.5) forms precipitates when mixed with acidic drugs such as opioids, muscle relaxants, catecholamines and Ringer's lactate, and must be given through a dedicated flushed line.
What Is Thiopental Panpharma and What Is It Used For?
Thiopental Panpharma is an ultra-short-acting barbiturate administered intravenously by anesthesiologists to rapidly induce general anesthesia for surgery, to sedate critically ill patients in intensive care, to treat refractory status epilepticus and to reduce raised intracranial pressure in patients with traumatic brain injury or cerebral edema.
Thiopental sodium, the active ingredient in Thiopental Panpharma, is a thiobarbiturate derivative first synthesized in the 1930s and introduced into clinical anesthesia in 1934. It is one of the most historically important intravenous anesthetic agents and, despite the emergence of newer drugs such as propofol and etomidate, remains a key medicine on the World Health Organization (WHO) Model List of Essential Medicines. In many countries it continues to be used when a predictable, rapid-onset induction agent with known neuroprotective properties is required.
Pharmacologically, thiopental is classified as an ultra-short-acting barbiturate. It acts primarily at the gamma-aminobutyric acid type A (GABA-A) receptor complex in the central nervous system, where it functions as a positive allosteric modulator. By prolonging the time that chloride channels remain open in response to GABA, thiopental enhances inhibitory neurotransmission and produces a continuum of effects ranging from sedation through hypnosis to deep general anesthesia. At high doses it directly activates GABA-A receptors even in the absence of GABA, explaining its ability to cause isoelectric electroencephalographic activity when used for cerebral protection.
Clinically, Thiopental Panpharma is used in several well-defined scenarios. The most common indication is induction of general anesthesia before elective and emergency surgery, including rapid sequence induction in patients at risk of aspiration. It is also used as the sole anesthetic agent for very short procedures such as electroconvulsive therapy (ECT), cardioversion, reduction of fractures and minor endoscopic interventions. In neurointensive care, thiopental is given in continuous infusion to control refractory status epilepticus when first- and second-line anticonvulsants have failed, and to lower intracranial pressure by reducing cerebral metabolic rate and cerebral blood flow in patients with severe head injury or post-cardiac-arrest brain injury.
Because of its ability to suppress cerebral metabolism, thiopental has been investigated as a neuroprotective agent in cardiac surgery and carotid endarterectomy, although the evidence base for routine prophylactic use in these settings remains mixed. A single intravenous bolus crosses the blood-brain barrier within one arm-brain circulation time (20-30 seconds), producing smooth loss of consciousness without the excitatory phenomena sometimes seen with other anesthetics. Recovery from a single induction dose occurs by rapid redistribution from the highly perfused brain to muscle and fat tissue, rather than by metabolism or excretion, which explains the short clinical duration despite a long terminal elimination half-life of 6 to 12 hours.
Thiopental Panpharma is not a patient-administered medicine. It is given exclusively within hospitals, operating theatres and critical care units by, or under the direct supervision of, an anesthesiologist or intensivist who is fully trained in advanced airway management and cardiovascular resuscitation. The information in this guide is intended to help patients, caregivers and non-specialist clinicians understand how the drug is used and what to expect; it does not replace the Summary of Product Characteristics or local institutional protocols.
What Should You Know Before Receiving Thiopental Panpharma?
Before thiopental is administered, the anesthetist will review your medical history in detail, paying particular attention to porphyria, heart disease, respiratory conditions, severe liver or kidney impairment, allergies and current medications. Certain conditions are absolute contraindications; others require dose reduction, enhanced monitoring or use of an alternative induction agent.
A thorough preanesthetic assessment is mandatory before the administration of any general anesthetic, including thiopental. This assessment usually takes place during a preoperative consultation and includes a complete medical history, physical examination, airway evaluation, review of prior anesthetic experiences, family history of anesthetic complications and relevant laboratory or imaging investigations. The findings determine whether thiopental is the most appropriate induction agent or whether an alternative such as propofol, etomidate or ketamine should be chosen.
Patients should disclose all prescription medicines, over-the-counter drugs, recreational substances, herbal preparations and dietary supplements they use. Alcohol, benzodiazepines, opioids and antihypertensive drugs all interact with thiopental and may necessitate dose adjustment. Fasting guidelines from the European Society of Anaesthesiology and Intensive Care (ESAIC) should be followed: typically 6 hours for solid foods and milk, and 2 hours for clear fluids, unless modified for specific clinical situations.
Contraindications
Thiopental Panpharma has a small number of absolute contraindications that must be identified before administration. These include any of the acute hepatic porphyrias, including acute intermittent porphyria, variegate porphyria and hereditary coproporphyria. Barbiturates are among the most potent inducers of the heme biosynthetic enzyme delta-aminolevulinic acid synthase (ALAS-1) and can trigger life-threatening porphyric crises characterized by severe abdominal pain, neurological deterioration, seizures and autonomic instability. Any patient with a personal or family history suggestive of porphyria should undergo biochemical screening before exposure to barbiturates.
Other absolute contraindications include known hypersensitivity to thiopental or to any other barbiturate, status asthmaticus, severe uncontrolled cardiovascular disease in which myocardial depression would be poorly tolerated, and any situation in which intravenous access, airway management and immediate resuscitation cannot be guaranteed. The dry powder contains sodium carbonate, so patients on strict sodium-restricted diets should be evaluated, although the sodium load from a single induction dose is clinically negligible.
Relative contraindications, in which the risks and benefits must be carefully weighed, include severe hepatic impairment (delayed recovery due to reduced metabolism), severe renal failure (altered protein binding and delayed elimination of metabolites), significant hypovolemia, shock, severe anemia, myasthenia gravis, dystrophia myotonica, adrenal insufficiency, severe cachexia and advanced age. In all these groups, substantially reduced doses and slower administration rates are required, and alternative agents with more favorable cardiovascular profiles, such as etomidate or ketamine, are often preferred.
Warnings and Precautions
Thiopental produces dose-dependent respiratory and cardiovascular depression. After a standard induction dose, apnea lasting 30 to 90 seconds is the norm, and a fall in systemic arterial pressure of 10 to 20 percent is expected. These effects are exaggerated in patients with hypovolemia, cardiac failure, pericardial tamponade, constrictive pericarditis or severe coronary artery disease. Preoperative volume optimization, slow titration, and readiness to give vasopressors (for example phenylephrine or ephedrine) are essential.
Accidental extravasation of thiopental into subcutaneous tissue causes severe local pain, inflammation and, rarely, tissue necrosis because of the drug's strong alkalinity. Inadvertent intra-arterial injection is a medical emergency: it produces immediate burning pain, arterial spasm, crystal formation within the vessel and may result in distal ischemia, thrombosis and gangrene. Management includes leaving the cannula in place, administering an intra-arterial vasodilator (such as papaverine or lidocaine), systemic anticoagulation and urgent vascular surgical consultation. Always use a large peripheral or central vein with demonstrated good flow, and flush the line thoroughly both before and after injection.
Laryngospasm, bronchospasm, coughing and hiccups may occur during induction, particularly in patients with active upper respiratory tract infections, heavy smokers or those with reactive airway disease. Although thiopental does not release histamine to the same extent as some other induction drugs, it blunts airway reflexes less effectively than propofol, which makes it a suboptimal choice for procedures requiring laryngeal mask insertion without muscle relaxants. Facial, upper airway and oral instrumentation should therefore be delayed until an adequate depth of anesthesia has been established.
Prolonged infusion of thiopental, as used in refractory status epilepticus or for intracranial pressure control, can lead to cumulative saturation of fat and muscle compartments, resulting in an apparent elimination half-life of up to 60 hours and delayed awakening lasting days. During such infusions, continuous EEG monitoring is essential, together with close attention to hemodynamic support, infection surveillance (thiopental is immunosuppressive), and prevention of pressure ulcers, deep vein thrombosis and gastrointestinal stasis.
Pregnancy, Breastfeeding and Pediatric Considerations
Thiopental crosses the placenta within seconds of intravenous administration and equilibrates rapidly between maternal and fetal circulations. It is nevertheless one of the most widely used induction agents for general anesthesia in obstetric practice, including cesarean section, and has an extensive safety record when used at induction doses of up to 4 mg per kilogram. Higher doses may cause transient neonatal respiratory depression and reduced Apgar scores, particularly if the induction-to-delivery interval exceeds 10 minutes. A pediatrician or neonatologist capable of neonatal resuscitation should be present at delivery whenever general anesthesia has been used.
Thiopental is excreted into breast milk in small amounts. After a single induction dose, the estimated infant exposure is well below the levels associated with clinical effects, but most guidelines recommend a temporary interruption of breastfeeding for 4 to 12 hours, or discarding milk expressed during this period, particularly in preterm or medically fragile infants. Breastfeeding may resume once the mother is alert and able to care for the infant safely.
In pediatric anesthesia, thiopental has been used safely for decades, although propofol and sevoflurane have largely replaced it in many centers for elective induction. Neonates require lower weight-based doses (approximately 3 to 4 mg/kg) because of immature hepatic metabolism and an increased proportion of body water, whereas infants and toddlers may need slightly higher doses (5 to 8 mg/kg) than adults to compensate for a relatively larger central volume of distribution. Intravenous access in small children should be secured before induction whenever feasible, and all pediatric administration demands equipment and staff appropriate for the child's age and weight.
Any patient who develops severe abdominal pain, confusion, seizures, dark or red-colored urine or motor weakness after receiving a barbiturate must be urgently investigated for an acute porphyric attack. In addition, rare but life-threatening anaphylactic and anaphylactoid reactions to thiopental have been reported. Resuscitation drugs, including adrenaline, intravenous fluids, chlorphenamine and hydrocortisone, must always be immediately available when thiopental is administered.
How Does Thiopental Panpharma Interact with Other Drugs?
Thiopental interacts with a broad range of medications through both pharmacokinetic (enzyme induction, altered protein binding) and pharmacodynamic (additive central nervous system or cardiovascular depression) mechanisms. The anesthetist must be aware of all drugs the patient is taking, including herbal supplements and recreational substances, before induction.
Pharmacodynamically, thiopental's central nervous system depressant effects are potentiated by all other CNS depressants. Concomitant administration with opioid analgesics, benzodiazepines, volatile anesthetics, ethanol, phenothiazines, sedating antihistamines and antipsychotics increases the risk, depth and duration of respiratory depression, hypotension and loss of airway reflexes. These combinations are intentional in clinical anesthesia but require careful titration and sometimes dose reduction of the induction agent. Acute alcohol intoxication and chronic alcoholism both alter thiopental requirements: acute intoxication lowers the required dose, while chronic heavy drinking induces hepatic enzymes and may increase the dose needed because of enhanced metabolism and cross-tolerance.
Pharmacokinetic interactions occur primarily at the level of the cytochrome P450 system and plasma protein binding. Barbiturates are classic enzyme inducers, upregulating CYP1A2, CYP2C9, CYP2C19 and CYP3A4 with repeated exposure, which may accelerate the clearance of medicines such as warfarin, oral contraceptives, corticosteroids, antiretrovirals and certain anticonvulsants. Although this induction is clinically relevant mostly with prolonged infusion, a single exposure can still subtly perturb metabolism of tightly regulated drugs. Thiopental is highly protein-bound (approximately 80-85 percent), and displacement by sulfonamides, aspirin, phenylbutazone or probenecid can transiently increase the free (active) fraction and deepen central nervous system effects.
Muscle relaxants interact with thiopental both physicochemically and pharmacologically. Non-depolarizing relaxants (rocuronium, vecuronium, atracurium, cisatracurium) are commonly given after induction; however, they are acidic solutions that precipitate on contact with the alkaline thiopental solution in the same intravenous line. A thorough saline flush is essential between drugs. Depolarizing relaxants (suxamethonium) are pharmacologically compatible but must similarly not share the same syringe. Catecholamines such as adrenaline, noradrenaline, dopamine and dobutamine are inactivated by the alkaline environment and must never be mixed with thiopental.
Major Drug Interactions
| Drug / Drug Class | Type of Interaction | Clinical Significance | Recommendation |
|---|---|---|---|
| Opioids (fentanyl, morphine, remifentanil) | Pharmacodynamic (additive CNS depression) | Deeper respiratory depression, profound hypotension | Intentional coadministration - reduce thiopental dose 25-50%; prepare for vasopressor support |
| Benzodiazepines (midazolam, diazepam) | Pharmacodynamic (additive GABA-ergic effect) | Prolonged sedation, respiratory depression | Reduce thiopental induction dose; titrate slowly |
| Volatile anesthetics (sevoflurane, isoflurane, desflurane) | Pharmacodynamic (synergistic anesthesia) | Enhanced cardiovascular depression | Careful titration of volatile concentration after induction |
| Non-depolarizing muscle relaxants (rocuronium, atracurium) | Physicochemical incompatibility | Precipitation within IV line, line occlusion | Never mix; flush line with 10-20 mL saline between drugs |
| Catecholamines (adrenaline, noradrenaline, dopamine) | Chemical degradation in alkaline pH | Loss of pressor activity | Use separate IV line or thoroughly flush before administration |
| Probenecid | Pharmacokinetic (protein binding displacement) | Increased free thiopental, deeper anesthesia | Reduce induction dose; monitor hemodynamics closely |
| Sulfonamides and aspirin | Pharmacokinetic (protein binding displacement) | Potentiation of thiopental effect | Cautious titration; avoid bolus overdose |
| Warfarin and oral contraceptives | Pharmacokinetic (CYP induction, with repeated dosing) | Reduced anticoagulation / contraceptive efficacy | Monitor INR; use additional contraceptive method for 4 weeks |
Other Notable Interactions
| Drug / Substance | Mechanism | Clinical Relevance |
|---|---|---|
| Ethanol (acute intoxication) | Additive CNS depression | Lower induction dose required |
| Ethanol (chronic use) | Enzyme induction, cross-tolerance | Higher induction dose may be required |
| Phenytoin, carbamazepine, rifampicin | CYP induction | Possibly shortened clinical effect with infusion |
| Antihypertensive agents | Additive hemodynamic depression | Exaggerated fall in blood pressure at induction |
| Ketamine | Opposing cardiovascular effects | Combination may offset hypotension but complicates titration |
| St John's Wort (Hypericum) | CYP3A4 induction | Discontinue at least 5 days before elective surgery when possible |
Reconstituted thiopental has a strongly alkaline pH (approximately 10.5). It is chemically incompatible with virtually all acidic drugs, including opioids, muscle relaxants, catecholamines, midazolam, atropine, ondansetron and Ringer's lactate. If only one intravenous line is available, flush with 10-20 mL of 0.9 percent sodium chloride both before and after each thiopental injection. Whenever possible, use a dedicated line for thiopental during continuous infusion.
What Is the Correct Dosage of Thiopental Panpharma?
Thiopental is dosed to effect rather than by a fixed schedule. Typical adult induction doses range from 3 to 5 mg per kilogram of body weight, administered as a 2.5 percent solution (25 mg/mL) over 20 to 30 seconds. Doses for children, elderly, debilitated, hypovolemic or critically ill patients must be substantially reduced and titrated carefully under continuous monitoring.
The correct dose of thiopental depends on the clinical indication, the patient's age, weight, cardiovascular status, concomitant medications, and whether it is given as a single bolus, repeated bolus or continuous infusion. Because individual responses vary, it is standard anesthetic practice to inject a small test dose first (for example 25 to 75 mg in adults), observe the patient's response, and then titrate further 50 to 100 mg boluses every 20 to 40 seconds until the desired depth of anesthesia is achieved, typically defined by loss of the eyelash reflex.
Thiopental Panpharma 0.5 g is most commonly reconstituted to a 2.5 percent solution by adding 20 mL of sterile water for injection or 0.9 percent sodium chloride to the vial, giving a concentration of 25 mg per milliliter. Higher concentrations increase the risk of severe tissue injury from extravasation or intra-arterial injection and are generally avoided. Reconstituted solutions should be used within 24 hours, stored at room temperature and protected from light. Any solution that shows turbidity, crystals or a precipitate must be discarded.
Adults
Induction of General Anesthesia in Adults
Healthy adults (ASA physical status I-II) typically require 3 to 5 mg per kilogram of lean body weight to achieve loss of consciousness. For a 70 kg adult this corresponds to approximately 210 to 350 mg, equivalent to 8 to 14 mL of a 2.5 percent solution. The dose is injected intravenously over 20 to 30 seconds; rapid bolus injection worsens hypotension and apnea without increasing depth of anesthesia. If the first increment is insufficient, additional 50 to 100 mg boluses are given every 20 to 40 seconds until adequate anesthesia is reached.
For short procedures of less than 15 minutes, anesthesia can be maintained by intermittent boluses of 50 to 100 mg or by infusion at 0.5 to 2 mg/kg/hour. For longer surgery, thiopental is almost exclusively used as a single induction agent, with maintenance provided by volatile anesthetics, propofol or total intravenous anesthesia techniques, because of its prolonged context-sensitive half-time.
Status Epilepticus Refractory to First- and Second-Line Therapy
In intensive care, a loading dose of 3 to 5 mg/kg followed by continuous infusion titrated to burst suppression on continuous EEG (typically 3 to 5 mg/kg/hour, occasionally up to 10 mg/kg/hour) may be used. Treatment usually continues for 24 to 48 hours of seizure control, followed by a gradual weaning of the infusion over 12 to 24 hours. Close hemodynamic support, invasive monitoring and vasopressor therapy are almost always required.
Raised Intracranial Pressure
A loading dose of 1.5 to 3 mg/kg followed by infusion of 1 to 5 mg/kg/hour titrated to intracranial pressure goals and EEG burst suppression has been used in traumatic brain injury and refractory intracranial hypertension. The benefit is weighed against the risks of hypotension, prolonged awakening, immunosuppression and increased pneumonia rates; current neurocritical care guidelines reserve barbiturate coma for carefully selected patients.
Children and Adolescents
Pediatric Induction Doses
Thiopental has been used safely in pediatric anesthesia for decades. Typical induction doses are:
- Neonates (0-28 days): 3-4 mg/kg intravenously
- Infants (1-12 months): 5-8 mg/kg intravenously
- Children (1-12 years): 5-7 mg/kg intravenously
- Adolescents (12-18 years): 3-5 mg/kg, as for adults
As with adults, the dose is injected slowly and titrated to effect. Propofol is generally preferred for elective pediatric anesthesia in centers where it is available, but thiopental remains valuable for rapid sequence induction, in hemodynamically unstable children, and in settings where propofol supply is limited.
Elderly Patients
Geriatric Dosage Considerations
Patients older than 65 years show increased sensitivity to thiopental due to reduced lean body mass, decreased cardiac output, slower drug redistribution and lower plasma protein binding. Induction doses should start at 2 to 3 mg/kg and be titrated slowly. Blood pressure falls more steeply and apnea lasts longer than in younger adults. Cautious coadministration of opioids and benzodiazepines, continuous hemodynamic monitoring and readiness to give vasopressors are essential. Whenever possible, etomidate or propofol with careful titration may be preferred in frail elderly patients with cardiovascular disease.
Renal and Hepatic Impairment
Dose Modification in Organ Dysfunction
In severe hepatic impairment, reduced drug metabolism and hypoalbuminemia (which increases the free drug fraction) call for a dose reduction of 30 to 50 percent and slower titration. In severe renal failure, protein binding is also decreased and metabolites accumulate, so reduced initial doses (2 to 3 mg/kg) and longer dosing intervals during infusion are advisable. Thiopental is not significantly removed by hemodialysis because of its high lipid solubility and protein binding.
Missed Dose
As Thiopental Panpharma is not a self-administered medication but is given under direct medical supervision as part of a planned procedure or intensive care protocol, the concept of a "missed dose" does not apply in the usual sense. If a planned procedure is postponed, the anesthetist will simply not administer the drug. During continuous infusions in critical care, any interruption of the infusion should be documented and reported to the treating team, as seizures may recur in status epilepticus and intracranial pressure may rise rapidly in neurointensive care patients.
Overdose
Thiopental overdose is primarily a clinical concern during administration and typically manifests as profound respiratory depression, severe hypotension, loss of airway reflexes, hypothermia and circulatory collapse. There is no specific antidote. Management is supportive and includes immediate airway protection and mechanical ventilation with 100 percent oxygen, intravenous fluid resuscitation, vasopressors (noradrenaline, phenylephrine) and inotropes as required, active rewarming and continuous cardiovascular monitoring in an intensive care setting. Forced diuresis, hemodialysis and hemoperfusion are of limited value because of the drug's high lipid solubility and protein binding, although hemoperfusion has been used in massive overdoses.
| Patient Group | Recommended Induction Dose | Notes |
|---|---|---|
| Healthy adults (ASA I-II) | 3-5 mg/kg IV | Titrate in 50-100 mg increments; typical 70 kg patient 210-350 mg |
| Elderly (≥65 years) | 2-3 mg/kg IV | Slower injection; anticipate hypotension and prolonged apnea |
| Children (1-12 years) | 5-7 mg/kg IV | Pediatric anesthetist supervision; age-appropriate equipment |
| Infants (1-12 months) | 5-8 mg/kg IV | Relatively higher doses due to larger volume of distribution |
| Neonates (0-28 days) | 3-4 mg/kg IV | Immature hepatic metabolism; slower titration |
| Cesarean section | 3-4 mg/kg IV | Limit dose; neonatal resuscitation team available |
| Hypovolemic / shock | 0.5-2 mg/kg IV | Consider etomidate or ketamine instead; volume resuscitate first |
| Severe hepatic impairment | Reduce by 30-50% | Prolonged effect; closer postoperative monitoring |
| Severe renal impairment | 2-3 mg/kg IV | Watch for metabolite accumulation in prolonged use |
| Status epilepticus (ICU) | 3-5 mg/kg load, then 3-5 mg/kg/h | Continuous EEG; titrate to burst suppression |
What Are the Side Effects of Thiopental Panpharma?
Thiopental causes predictable, dose-dependent cardiorespiratory depression - apnea and hypotension are expected at induction and are managed as part of routine anesthesia. Less common but clinically important side effects include laryngospasm, bronchospasm, thrombophlebitis, allergic reactions and, rarely, severe tissue injury after extravasation or intra-arterial injection.
Adverse effects of thiopental are most often classified by frequency according to the Council for International Organizations of Medical Sciences (CIOMS) convention: very common (at least 1 in 10 patients), common (1 in 10 to 1 in 100), uncommon (1 in 100 to 1 in 1,000), and rare or very rare (fewer than 1 in 1,000). Because thiopental is given almost exclusively in a monitored perioperative environment, many "side effects" (apnea, hypotension) are expected pharmacological effects rather than complications.
Cardiovascular effects dominate the profile. Thiopental produces a dose-dependent fall in systemic vascular resistance and myocardial contractility, with compensatory tachycardia. In healthy patients this rarely causes problems, but in hypovolemic, septic, frail or cardiac-compromised patients it can precipitate severe hypotension. Respiratory effects include apnea lasting from seconds to several minutes, blunted airway reflexes, and a tendency to airway irritability that can manifest as laryngospasm or bronchospasm, particularly in smokers, asthmatics or patients with upper respiratory tract infections.
Neurological and psychological effects include drowsiness, headache, paradoxical restlessness during emergence, anterograde amnesia (usually beneficial) and, uncommonly, emergence delirium. Unlike ketamine, thiopental does not cause hallucinations, although unpleasant dreams are occasionally reported. Local injection-site reactions include pain on injection, thrombophlebitis and, rarely, necrotizing ulceration after extravasation. Immunological reactions range from minor rashes and urticaria to anaphylactic shock with an estimated incidence of approximately 1 in 30,000 administrations.
Very Common Side Effects
May affect more than 1 in 10 people
- Apnea lasting 30-90 seconds after induction bolus
- Transient hypotension (fall in blood pressure of 10-20 percent)
- Reflex tachycardia
- Drowsiness and anterograde amnesia
Common Side Effects
May affect up to 1 in 10 people
- Coughing, hiccups or sneezing during induction
- Headache on emergence
- Nausea and vomiting in the recovery period
- Shivering (postanesthetic)
- Venous irritation or thrombophlebitis at the injection site
- Paradoxical restlessness during emergence
Uncommon Side Effects
May affect up to 1 in 100 people
- Laryngospasm
- Bronchospasm, especially in asthmatic patients
- Arrhythmias (most often supraventricular)
- Skin rash, urticaria, pruritus
- Emergence delirium
- Prolonged awakening, particularly after repeated or infused doses
Rare and Very Rare Side Effects
May affect fewer than 1 in 1,000 people
- Anaphylactic or anaphylactoid reactions
- Severe tissue necrosis following extravasation
- Intra-arterial injection with distal ischemia and gangrene
- Acute porphyric crisis in susceptible individuals
- Agranulocytosis or thrombocytopenia (reported during prolonged infusion)
- Severe myocardial depression leading to cardiac arrest
- Hepatotoxicity (very rare, with prolonged exposure)
Anaphylaxis (facial or airway swelling, widespread urticaria, severe bronchospasm, sudden cardiovascular collapse), severe laryngospasm that does not resolve with positive pressure ventilation, signs of intra-arterial injection (severe pain distal to the injection site, blanching, mottling), or any suggestion of an acute porphyric attack (severe abdominal pain, confusion, dark urine, new neurological deficits). In the perioperative setting, resuscitation follows standard advanced life support and local anesthesia emergency protocols.
All suspected adverse drug reactions should be reported to the relevant national pharmacovigilance authority (for example the Medicines and Healthcare products Regulatory Agency in the United Kingdom, the Food and Drug Administration MedWatch program in the United States, or the European Medicines Agency through EudraVigilance for member states). Reporting supports ongoing safety surveillance for thiopental, which has been in clinical use for nearly a century.
How Should Thiopental Panpharma Be Stored and Handled?
Unreconstituted Thiopental Panpharma 0.5 g vials must be stored below 25 degrees Celsius in their original carton to protect from light. After reconstitution with sterile water or 0.9 percent sodium chloride, the 2.5 percent solution is chemically stable at room temperature for 24 hours but should, whenever possible, be drawn up immediately before use.
Thiopental Panpharma is supplied as a sterile, yellowish, freeze-dried powder in a glass vial, accompanied by pharmaceutical-grade anhydrous sodium carbonate which adjusts the pH after reconstitution to approximately 10.5. The carton should be stored in a hospital pharmacy or dedicated drug cupboard at a temperature not exceeding 25 degrees Celsius, away from direct light and heat sources. The vial must not be frozen.
Reconstitution is usually performed using strict aseptic technique by adding 20 mL of sterile water for injection or 0.9 percent sodium chloride to the 0.5 g vial, producing a 25 mg/mL (2.5 percent) solution. The vial is gently rotated (not vigorously shaken) until the powder is fully dissolved. The reconstituted solution should be clear and slightly yellow; any preparation that shows turbidity, visible crystals, precipitate or discoloration must be discarded. The label must be checked against the prescription immediately before administration.
Because thiopental is chemically stable for up to 24 hours at room temperature after reconstitution, unused reconstituted solution from a single-patient vial may in principle be kept for later use within the same anesthetic case; however, most institutional policies recommend preparation immediately before use and discarding any unused solution at the end of the case. Reconstituted solutions must not be refrigerated, as cold temperatures may cause the drug to precipitate out of solution.
Thiopental, like all barbiturates, is subject to national regulations on controlled substances in many countries and must be stored, accessed, dispensed and documented in accordance with local legal requirements. This typically includes secure storage, witnessed withdrawal, accurate record-keeping of each dose, and formal waste disposal procedures. Hospitals must also maintain robust chain-of-custody procedures because of the non-medical use of thiopental in capital punishment in some jurisdictions, which has led to international supply restrictions.
Unused reconstituted solution and expired vials must not be disposed of in general waste or flushed down drains. They should be returned to the hospital pharmacy or an authorized controlled-drug disposal service in accordance with local environmental protection and controlled-substance regulations. Proper disposal prevents accidental human or animal exposure and protects waterways from pharmaceutical contamination.
What Does Thiopental Panpharma Contain?
Each vial of Thiopental Panpharma contains 0.5 g (500 mg) of thiopental sodium as the active ingredient, together with anhydrous sodium carbonate as a pH-adjusting excipient. The powder is reconstituted with sterile water for injection or 0.9 percent sodium chloride immediately before use to form a 2.5 percent intravenous solution.
The active ingredient, thiopental sodium, is the sodium salt of 5-ethyl-5-(1-methylbutyl)-2-thiobarbituric acid. Its chemical structure differs from the parent compound pentobarbital only by the substitution of a sulfur atom for oxygen at the 2-position of the barbituric acid ring, a modification that greatly increases lipid solubility and accounts for the drug's exceptionally rapid onset of central nervous system effect after intravenous administration. The molecular formula is C11H17N2NaO2S, with a molecular weight of approximately 264.3 g/mol.
The single excipient is anhydrous sodium carbonate (Na2CO3), which confers the alkaline pH necessary to keep thiopental in solution as the ionized sodium salt. In the aqueous environment of blood (pH 7.4), thiopental exists predominantly in its non-ionized, highly lipid-soluble form, which is why it crosses the blood-brain barrier so rapidly. The strongly alkaline pH is also responsible for the drug's irritant effect on veins and for its numerous physicochemical incompatibilities with acidic medicines.
The vial itself is pharmaceutical-grade neutral borosilicate glass sealed with a butyl rubber stopper and an aluminum overseal with a plastic flip-off cap. The powder inside is a pale yellow to yellowish amorphous mass under reduced pressure. Vials contain no preservatives, antioxidants or bacteriostatic agents, and any vial showing color change, visible moisture or loss of vacuum should not be used.
Patients with known allergies or hypersensitivity to any barbiturate, to sulfur-containing compounds, or to sodium should be carefully evaluated before administration. The sodium content of a single 0.5 g dose (approximately 35 mg of sodium) is clinically insignificant for most patients, but may become relevant during prolonged high-dose infusions in patients on strict sodium restriction or with severe heart failure.
Frequently Asked Questions About Thiopental Panpharma
Thiopental Panpharma is an ultra-short-acting barbiturate used intravenously by anesthesiologists for four main indications: induction of general anesthesia before surgery or procedures; anesthesia for brief interventions such as electroconvulsive therapy, cardioversion and fracture reduction; treatment of refractory status epilepticus when first-line anticonvulsants have failed; and reduction of raised intracranial pressure in traumatic brain injury or cerebral edema. It produces loss of consciousness within 30 to 60 seconds of intravenous administration and is a medicine on the WHO Model List of Essential Medicines.
Thiopental has one of the fastest onsets of any intravenous anesthetic. Loss of consciousness typically occurs within 30 to 60 seconds of injection, which corresponds to a single arm-brain circulation time. Clinical anesthesia from a single induction dose lasts approximately 5 to 10 minutes because thiopental is rapidly redistributed from the brain to muscle and fat. Despite this short clinical effect, the terminal elimination half-life is 6 to 12 hours, so residual drowsiness, impaired judgment and reduced coordination can persist for several hours after a single induction dose, and even longer after continuous infusions.
Thiopental is absolutely contraindicated in patients with acute intermittent porphyria, variegate porphyria or hereditary coproporphyria, because it can trigger life-threatening porphyric crises. Other contraindications include known hypersensitivity to thiopental or any other barbiturate, status asthmaticus, severe uncompensated cardiovascular disease, and any situation in which intravenous access, airway management and immediate resuscitation cannot be guaranteed. Relative contraindications, requiring dose reduction or an alternative induction agent, include severe liver or kidney failure, shock, severe anemia, myasthenia gravis, adrenal insufficiency and advanced age with frailty.
The most common and predictable side effects are dose-dependent cardiorespiratory depression, with apnea lasting 30 to 90 seconds and a fall in blood pressure of 10 to 20 percent after induction. Other common effects include coughing or hiccups during injection, headache, nausea and shivering in recovery, and venous irritation at the injection site. Less common but important effects are laryngospasm, bronchospasm (particularly in asthmatics), prolonged awakening, and rare allergic reactions including anaphylaxis. Extravasation or accidental intra-arterial injection can cause severe tissue damage and require urgent treatment.
Yes. Thiopental has been used in pediatric anesthesia for decades and remains an option for induction of general anesthesia in children. Neonates require lower doses (around 3 to 4 mg per kilogram), while infants and young children often need higher weight-based doses (5 to 8 mg per kilogram) than adults due to a larger central volume of distribution. In many contemporary pediatric anesthesia practices, propofol has become the first-line induction agent, but thiopental remains valuable for rapid sequence induction, hemodynamically unstable children and settings where propofol is unavailable. All pediatric administration must be performed by clinicians trained in pediatric airway management with age-appropriate equipment on hand.
Thiopental crosses the placenta and can cause neonatal respiratory depression if given in high doses, particularly with a long induction-to-delivery interval. However, at induction doses up to 4 mg per kilogram it has a long record of use for cesarean section and is not considered teratogenic. A neonatal team capable of resuscitation should always be present at delivery. Thiopental is excreted in small amounts into breast milk; a brief interruption of breastfeeding (4 to 12 hours) after a single induction dose is often recommended, especially for preterm or medically fragile infants, but breastfeeding can resume once the mother is alert and able to care for the baby safely.
Thiopental Panpharma 0.5 g is a dry yellow powder that is reconstituted with 20 mL of sterile water for injection or 0.9 percent sodium chloride to produce a 2.5 percent (25 mg/mL) solution. The solution is injected slowly into a large, free-flowing peripheral or central vein over 20 to 30 seconds and titrated to loss of consciousness. Because the solution is strongly alkaline (pH approximately 10.5), it must not be mixed with acidic drugs such as opioids, muscle relaxants or catecholamines; the intravenous line should be flushed with saline before and after administration. Reconstituted solution is used within 24 hours and should never be administered intramuscularly or subcutaneously.
Both thiopental and propofol are intravenous induction agents with rapid onset. Thiopental is an ultra-short-acting barbiturate that works at GABA-A receptors and has been in clinical use since 1934; it is supplied as an alkaline aqueous solution, is neuroprotective (reduces cerebral metabolic rate), and is traditionally favored in obstetric rapid sequence induction. Propofol is an alkyl phenol derivative in a lipid emulsion, allows smoother intravenous maintenance, has antiemetic properties, and produces a more rapid and clear-headed recovery. Propofol causes more hypotension at induction, can produce pain on injection and, in prolonged high-dose infusions, risks propofol infusion syndrome. The choice between the two depends on the clinical situation, patient comorbidities, and the anesthetist's expertise and preference.
References and Sources
This article is based on internationally recognized pharmacological and anesthesiological guidelines, peer-reviewed textbooks and regulatory information. All clinical content has been reviewed by qualified healthcare professionals and follows evidence-based principles.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List, 2023. Geneva: World Health Organization, 2023. Available at: www.who.int/publications
- European Medicines Agency (EMA). Guideline on Summary of Product Characteristics (SmPC): Intravenous Anaesthetics. EMA, 2024. Available at: www.ema.europa.eu
- Miller RD, Eriksson LI, Fleisher LA, Wiener-Kronish JP, Cohen NH, Young WL (Eds.). Miller's Anesthesia, 9th Edition. Elsevier, 2020. Chapter: Intravenous Anesthetics – Barbiturates.
- Stoelting RK, Hillier SC. Pharmacology and Physiology in Anesthetic Practice, 6th Edition. Wolters Kluwer, 2022.
- British National Formulary (BNF). Thiopental sodium. NICE, 2024. Available at: bnf.nice.org.uk
- U.S. Food and Drug Administration (FDA). Drug Safety Communications – Thiopental. FDA, 2024. Available at: www.fda.gov
- European Society of Anaesthesiology and Intensive Care (ESAIC). Guidelines for Pre-Operative Evaluation of the Adult Undergoing Non-Cardiac Surgery. Eur J Anaesthesiol, 2024.
- Goodman & Gilman's. The Pharmacological Basis of Therapeutics, 14th Edition. McGraw-Hill Education, 2023. Chapter: General Anesthetics and Therapeutic Gases.
- Anderson BJ, Larsson P. A pediatric pharmacology primer for the anesthetist. Paediatr Anaesth. 2011;21(3):222-237. doi:10.1111/j.1460-9592.2010.03475.x
- Brophy GM, Bell R, Claassen J, et al. Guidelines for the evaluation and management of status epilepticus. Neurocrit Care. 2012;17(1):3-23. doi:10.1007/s12028-012-9695-z
- International Council for Harmonisation (ICH). ICH E2C(R2): Periodic Benefit-Risk Evaluation Report. ICH, 2023.
- European Pharmacopoeia Commission. European Pharmacopoeia, 11th Edition – Monograph on Thiopental Sodium. Council of Europe, 2023.
About the Medical Editorial Team
This article has been written and reviewed by iMedic's Medical Editorial Team, consisting of licensed physicians and specialists in anesthesiology, clinical pharmacology and neurocritical care, with expertise in intravenous anesthetic agents, drug safety and evidence-based medicine.
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