Methadone Martindale Pharma: Uses, Dosage & Side Effects
A long-acting synthetic opioid oral solution used for opioid substitution therapy and management of severe chronic pain
Methadone Martindale Pharma is a 2 mg/ml oral solution containing methadone hydrochloride, a long-acting synthetic opioid agonist. It is primarily used as part of opioid substitution therapy (also known as opioid agonist therapy or medication-assisted treatment) for adults with opioid dependence, in conjunction with medical, social, and psychological support. Methadone is also used in the management of severe chronic pain where other strong opioid analgesics have been inadequate or poorly tolerated. Listed on the WHO Model List of Essential Medicines, methadone is a controlled substance requiring specialist prescription and supervised dispensing in most countries due to its potential for misuse, dependence, and serious adverse effects including respiratory depression and QT prolongation.
Quick Facts: Methadone Martindale Pharma
Key Takeaways
- Methadone Martindale Pharma is a long-acting opioid used primarily for opioid substitution therapy in adults with opioid dependence; it is on the WHO Model List of Essential Medicines and is a cornerstone of evidence-based addiction treatment worldwide.
- The drug carries serious risks of respiratory depression, QT prolongation, and death, particularly during treatment initiation and dose adjustments; careful dose titration under specialist supervision is essential.
- Never combine methadone with benzodiazepines, alcohol, or other central nervous system depressants without medical guidance, as the combination significantly increases the risk of fatal respiratory depression.
- Methadone has a uniquely long and variable half-life (8–59 hours), meaning that the full effect of a dose change may not be apparent for several days; dose increases must be made cautiously with adequate observation periods.
- Methadone maintenance is considered the standard of care for pregnant women with opioid use disorder by WHO and ACOG, as untreated dependence poses far greater risks to both mother and fetus than continued treatment.
What Is Methadone Martindale Pharma and What Is It Used For?
Methadone is a synthetic opioid that was first developed in Germany during the 1930s and 1940s and has been used in clinical medicine since 1947. It is a full agonist at the mu-opioid receptor (MOR), meaning it activates the same brain receptors as heroin, morphine, and other opioids. However, methadone has several pharmacological properties that distinguish it from shorter-acting opioids and make it uniquely suited for substitution therapy: a long duration of action that permits once-daily dosing, good oral bioavailability, gradual onset of effect (reducing euphoria compared to injected opioids), and additional activity at the NMDA receptor and as a monoamine reuptake inhibitor.
When taken as a regular oral dose under medical supervision, methadone produces a stable level of opioid activity in the brain that prevents withdrawal symptoms, reduces cravings for illicit opioids, and blocks the euphoric effects of additional opioid use through cross-tolerance. This pharmacological stabilization allows patients to participate in rehabilitation activities, maintain employment, reduce criminal behavior, and significantly lower the risk of overdose death and infectious disease transmission (HIV, hepatitis C) associated with injecting drug use.
The primary indications for Methadone Martindale Pharma include:
- Opioid substitution therapy (maintenance treatment): This is the most common indication. Methadone is prescribed as part of a comprehensive opioid agonist therapy (OAT) program for adults who are dependent on heroin or other opioids. The treatment aims to reduce illicit opioid use, prevent withdrawal symptoms, decrease the risk of overdose and infectious disease, and improve social functioning and quality of life. Treatment typically involves daily supervised consumption at a specialist clinic, with take-home doses granted as treatment progresses and stability is demonstrated.
- Medically supervised opioid withdrawal (detoxification): Methadone can be used to manage the symptoms of opioid withdrawal in a gradual dose-reduction protocol. The dose is incrementally reduced over days to weeks, providing a controlled and more comfortable withdrawal experience than abrupt cessation. However, evidence consistently shows that maintenance treatment has better long-term outcomes than detoxification alone, with significantly lower rates of relapse, overdose, and death.
- Severe chronic pain: Methadone is used as a second-line or third-line analgesic for severe chronic pain, particularly neuropathic pain, where its NMDA receptor antagonism may provide additional benefit. It is also used in cancer-related pain, especially when tolerance to other opioids has developed or when opioid rotation is needed. Pain management with methadone requires particular expertise due to its complex pharmacokinetics and the risk of QT prolongation.
Methadone is included on the WHO Model List of Essential Medicines, reflecting its critical role in global healthcare. The WHO, the United Nations Office on Drugs and Crime (UNODC), and numerous national health authorities recognize opioid agonist therapy with methadone or buprenorphine as the most effective treatment for opioid dependence, with Level 1A evidence from systematic reviews and meta-analyses of randomized controlled trials. The evidence demonstrates that methadone maintenance significantly reduces all-cause mortality, opioid-related overdose deaths, illicit drug use, criminal activity, and the transmission of blood-borne infections.
Methadone exerts its therapeutic effects through multiple mechanisms. As a full mu-opioid receptor agonist, it produces analgesia, suppresses withdrawal symptoms, and reduces cravings. It also acts as an antagonist at the N-methyl-D-aspartate (NMDA) receptor, which may contribute to its efficacy in neuropathic pain and in preventing the development of opioid tolerance. Additionally, methadone inhibits the reuptake of serotonin and norepinephrine, providing a monoaminergic component to its analgesic profile. The drug is well absorbed orally with a bioavailability of approximately 70–80%, reaches peak plasma concentrations in 2.5–4 hours, and has a long, variable elimination half-life of 8–59 hours (average approximately 22 hours), which allows for once-daily dosing in maintenance therapy.
Methadone is classified as a controlled substance in virtually all countries due to its potential for misuse, dependence, and diversion. In most jurisdictions, methadone for opioid dependence treatment can only be prescribed by or under the supervision of specially authorized physicians, and dispensing is typically subject to strict regulations including supervised consumption requirements. The oral solution formulation is specifically designed to facilitate supervised dosing at treatment clinics.
What Should You Know Before Taking Methadone Martindale Pharma?
Contraindications
There are specific medical situations where methadone must not be used. Understanding these absolute contraindications is essential for safe prescribing and patient safety.
- Hypersensitivity: Do not take methadone if you have a known allergy (hypersensitivity) to methadone hydrochloride or any of the other ingredients in the product.
- Respiratory depression: Methadone is contraindicated in patients with acute or severe respiratory depression, as it can further suppress breathing and may be fatal.
- Acute or severe bronchial asthma: Patients with uncontrolled or severe asthma are at significantly increased risk of life-threatening bronchospasm and respiratory failure.
- Known or suspected gastrointestinal obstruction: Including paralytic ileus, as methadone reduces gastrointestinal motility and can worsen obstruction.
- Concurrent use with MAO inhibitors: Do not take methadone if you are currently taking or have taken monoamine oxidase inhibitors (MAOIs) within the last 14 days, due to the risk of serotonin syndrome and severe unpredictable interactions.
- Raised intracranial pressure: Methadone can increase intracranial pressure and mask clinical signs in patients with head injury or raised intracranial pressure.
Warnings and Precautions
Serious, life-threatening, or fatal respiratory depression has been reported with the use of methadone, even when used as recommended. The risk is greatest during treatment initiation and following dose increases. Respiratory depression from methadone may occur later and persist longer than the analgesic effects because of its long and variable half-life (8–59 hours). Monitor patients closely for respiratory depression, especially within the first 72 hours of initiating therapy and following any dose increase. Instruct patients and caregivers to recognize the signs of respiratory depression and to seek emergency medical help immediately.
Methadone can cause dose-dependent prolongation of the QT interval on the electrocardiogram (ECG), which can lead to serious and potentially fatal cardiac arrhythmias including torsades de pointes. The risk increases with higher doses, electrolyte abnormalities (particularly low potassium, magnesium, or calcium), concomitant use of other QT-prolonging drugs, and pre-existing cardiac conditions. An ECG should be obtained before starting treatment, at dose stabilization, and periodically thereafter. Patients should be warned to seek medical attention if they experience palpitations, dizziness, lightheadedness, or fainting.
You should inform your doctor before taking methadone if any of the following conditions apply to you:
- Chronic respiratory disease: Patients with chronic obstructive pulmonary disease (COPD), cor pulmonale, significantly decreased respiratory reserve, hypoxia, hypercapnia, or pre-existing respiratory depression are at increased risk. Even recommended doses of methadone may decrease respiratory drive in these patients, potentially leading to apnea.
- Liver impairment: Methadone is extensively metabolized by the liver. Patients with hepatic impairment (including cirrhosis, which is common in the target population due to hepatitis C) may have reduced drug clearance, leading to increased plasma concentrations and prolonged effects. Lower starting doses and slower titration are recommended.
- Kidney impairment: Although renal excretion is a minor route of elimination, dose adjustments may be necessary in patients with moderate to severe kidney disease. Methadone metabolites accumulate in renal failure and may contribute to toxicity.
- Cardiac disease: Any patient with a history of cardiac arrhythmias, heart failure, structural heart disease, or congenital long QT syndrome is at increased risk of QT prolongation and torsades de pointes. An ECG assessment is mandatory in these patients.
- Electrolyte abnormalities: Hypokalemia, hypomagnesemia, and hypocalcemia predispose patients to QT prolongation. Electrolytes should be measured and corrected before starting methadone treatment.
- Hypothyroidism: Opioids, including methadone, can reduce thyroid function. Patients with pre-existing hypothyroidism may require closer monitoring and dose adjustment of thyroid replacement therapy.
- Adrenal insufficiency: Chronic opioid use can cause adrenal insufficiency, which may present as nausea, vomiting, loss of appetite, fatigue, weakness, dizziness, or low blood pressure. If diagnosed, treatment involves corticosteroid replacement and, if appropriate, gradual tapering of the opioid.
- Elderly patients: Older adults are more susceptible to the respiratory depressant and sedative effects of methadone. They may also have age-related decreases in liver and kidney function. Lower starting doses and careful titration are essential.
- History of seizures: Methadone may lower the seizure threshold. Use with caution in patients with a history of epilepsy or other seizure disorders.
- Risk of falls: Methadone can cause dizziness, drowsiness, and orthostatic hypotension, increasing the risk of falls, particularly in elderly patients. Patients should be advised to rise slowly from sitting or lying positions.
Pregnancy and Breastfeeding
Methadone maintenance treatment is considered the standard of care for pregnant women with opioid use disorder according to guidelines from the WHO, the American College of Obstetricians and Gynecologists (ACOG), the Royal College of Obstetricians and Gynaecologists (RCOG), and numerous other international medical bodies. Untreated opioid dependence during pregnancy is associated with significantly greater risks including miscarriage, preterm birth, fetal growth restriction, placental abruption, preeclampsia, low birth weight, stillbirth, and maternal death from overdose.
Women who are stable on methadone maintenance should generally continue treatment throughout pregnancy. The methadone dose may need to be increased during the second and third trimesters due to physiological changes in pregnancy (increased blood volume, enhanced hepatic metabolism, and increased renal clearance) that can reduce methadone plasma levels and precipitate withdrawal. Split dosing (twice-daily administration) may also be considered in later pregnancy to maintain stable plasma levels.
The newborn may experience neonatal abstinence syndrome (NAS), also called neonatal opioid withdrawal syndrome (NOWS), which typically presents 24–72 hours after birth. Symptoms include irritability, high-pitched crying, poor feeding, excessive sucking, tremors, sneezing, yawning, diarrhea, and, in severe cases, seizures. NAS is treatable and, while uncomfortable, is not life-threatening when properly managed. The severity of NAS does not reliably correlate with the maternal methadone dose, and reducing the methadone dose during pregnancy to prevent NAS is not recommended, as the risks of maternal relapse and fetal exposure to illicit substances far outweigh the risks of NAS.
Methadone is excreted in breast milk in small quantities. At standard maintenance doses, the amount transferred to the nursing infant is generally considered too small to have clinically significant effects, and breastfeeding is generally encouraged for women on stable methadone maintenance who are not using illicit substances and are not HIV-positive. Breastfeeding may also help mitigate NAS symptoms. Women should consult their prescriber and pediatrician for individualized advice.
Driving and Operating Machinery
Methadone can impair cognitive function, reaction time, and physical coordination, particularly during treatment initiation, dose adjustments, and when combined with other CNS depressants. Patients should be advised not to drive or operate heavy machinery until they are certain that methadone does not adversely affect their ability to engage in such activities. Once patients are stabilized on a maintenance dose and not experiencing sedation or other impairing effects, driving ability may not be significantly affected. However, each patient should be assessed individually, and local regulations regarding driving while on opioid agonist therapy should be followed.
How Does Methadone Martindale Pharma Interact with Other Drugs?
Methadone is extensively metabolized in the liver, primarily by cytochrome P450 enzymes CYP3A4, CYP2B6, and to a lesser extent CYP2D6 and CYP1A2. This makes it susceptible to a wide range of pharmacokinetic interactions. Additionally, methadone's pharmacodynamic properties (CNS depression, respiratory depression, QT prolongation) create the potential for dangerous additive effects with many other drug classes. A thorough medication review should be conducted before starting methadone and whenever any new medication is added.
Major Interactions
| Interacting Drug | Effect | Clinical Advice |
|---|---|---|
| Benzodiazepines (diazepam, alprazolam, clonazepam, etc.) | Concurrent use causes additive CNS and respiratory depression, dramatically increasing the risk of profound sedation, respiratory arrest, coma, and death | Avoid concomitant use whenever possible. If combination is unavoidable, use the lowest effective doses and shortest possible duration. Monitor closely for signs of respiratory depression and sedation. FDA Boxed Warning applies to this combination. |
| Rifampicin (rifampin) | Potent CYP3A4 inducer; can reduce methadone plasma concentrations by 33–68%, potentially precipitating severe opioid withdrawal syndrome | Avoid if possible. If rifampicin is essential, methadone dose may need to be substantially increased. Monitor closely for withdrawal symptoms and adjust dose accordingly. Consider rifabutin as an alternative with less enzyme induction. |
| Carbamazepine / Phenytoin / Phenobarbital | Strong CYP3A4 inducers that significantly reduce methadone plasma levels, risking withdrawal symptoms and treatment failure | Monitor for signs of opioid withdrawal. Methadone dose increase is usually required. Consider alternative anticonvulsants with fewer enzyme-inducing effects (e.g., valproate, levetiracetam). |
| Naltrexone / Naloxone | Opioid antagonists that directly block methadone's effects at the opioid receptor, precipitating acute and severe withdrawal syndrome | Do not administer naltrexone to patients on methadone. Naloxone should only be used in emergency overdose situations. Allow at least 7–10 days after last methadone dose before starting naltrexone. In overdose emergencies, naloxone may be needed but may require repeated dosing due to methadone's long half-life. |
| QT-prolonging medications (e.g., amiodarone, sotalol, erythromycin, haloperidol, certain antidepressants) | Additive QT prolongation, increasing the risk of torsades de pointes and sudden cardiac death | Obtain ECG monitoring when adding any QT-prolonging drug. Correct electrolyte abnormalities. Use the lowest effective methadone dose. Consider alternative medications with less QT risk where possible. |
| Alcohol | Additive CNS and respiratory depression; increased risk of fatal overdose, especially in combination with methadone | Strongly advise patients to avoid alcohol completely while taking methadone. Even moderate alcohol consumption with methadone significantly increases overdose risk. |
Minor Interactions
| Interacting Drug | Effect | Clinical Advice |
|---|---|---|
| Fluconazole / Voriconazole | CYP3A4 inhibitors that increase methadone plasma levels, potentially leading to excessive sedation, respiratory depression, and QT prolongation | Monitor for signs of opioid toxicity (excessive sedation, respiratory depression). Methadone dose reduction may be necessary. Consider ECG monitoring. |
| Ciprofloxacin | CYP1A2 inhibitor that can modestly increase methadone levels; also has QT-prolonging potential | Be aware of the dual risk of increased methadone levels and additive QT prolongation. Monitor patients clinically and consider ECG assessment. |
| Sertraline / Fluvoxamine | CYP enzyme inhibitors that can increase methadone plasma concentrations; also potential risk of serotonin syndrome with high-dose methadone | Monitor for signs of opioid excess and serotonin syndrome (agitation, confusion, rapid heart rate, elevated temperature, tremor). Dose adjustment may be needed. |
| St. John’s Wort (Hypericum perforatum) | CYP3A4 inducer that can reduce methadone levels and precipitate withdrawal symptoms | Patients should be advised to avoid St. John's Wort while taking methadone. If already using it, discontinuation should be gradual to avoid a sudden increase in methadone levels. |
| Antiretroviral drugs (efavirenz, nevirapine, ritonavir, lopinavir) | Complex interactions depending on the specific antiretroviral. Some (efavirenz, nevirapine) decrease methadone levels by inducing CYP3A4; others (ritonavir, lopinavir) may have mixed effects | Close monitoring is essential when starting, stopping, or changing antiretroviral therapy. Methadone dose adjustments are frequently needed. Consult HIV and addiction specialists collaboratively. |
Methadone, through its serotonin reuptake inhibiting properties, can contribute to serotonin syndrome when combined with other serotonergic medications including SSRIs, SNRIs, triptans, tricyclic antidepressants, tramadol, lithium, and the antibiotic linezolid. Symptoms of serotonin syndrome include agitation, confusion, rapid heartbeat, fever, excessive sweating, muscle rigidity or twitching, loss of coordination, nausea, vomiting, and diarrhea. Serotonin syndrome can be life-threatening and requires immediate medical attention.
What Is the Correct Dosage of Methadone Martindale Pharma?
Methadone dosing is complex and requires specialist expertise. The long and variable half-life means that steady-state plasma concentrations may not be reached for 3–10 days after a dose change, creating a risk of delayed toxicity if doses are increased too quickly. The following recommendations are based on international guidelines including the WHO, BNF, EMA SmPC, and SAMHSA clinical guidelines. Always follow your prescriber’s specific instructions.
Opioid Substitution Therapy (Adults)
Deaths have occurred during the induction phase of methadone treatment due to accumulation of methadone during the first few days. It is essential that the initial dose is kept low, dose increases are made gradually (no more frequently than every 3–5 days), and patients are carefully observed for signs of sedation and respiratory depression, particularly during the first 1–2 weeks. Patients should be assessed 3–4 hours after their first dose (approximate time of peak effect) to evaluate for signs of intoxication or over-sedation.
Induction Phase (Days 1–14)
Day 1: 10–30 mg as a single observed dose. The starting dose should be at the lower end (10–20 mg) for patients whose opioid tolerance is uncertain, who have low tolerance (e.g., recently released from prison, recently completed detoxification), or who are also using CNS depressants.
Day 2 onwards: If the initial dose was well tolerated and withdrawal symptoms persist, the dose may be increased by 5–10 mg. Dose increases should not be made more frequently than every 3–5 days to allow for drug accumulation.
Maximum first-week dose: A total daily dose of 40 mg should generally not be exceeded during the first week unless the patient is closely monitored in an inpatient setting.
Stabilization and Maintenance Phase
Dose range: Most patients require maintenance doses of 60–120 mg per day. Research consistently demonstrates that doses of at least 60 mg daily are associated with better treatment retention and outcomes, with many patients benefiting from doses of 80–120 mg or higher.
Adequacy of dose: The correct maintenance dose is one that prevents withdrawal for 24 hours, reduces or eliminates cravings, blocks the euphoric effects of illicit opioid use, and does not cause excessive sedation.
Administration: The oral solution should be administered once daily under direct observation (supervised consumption) at the dispensing clinic. Take-home doses may be granted progressively as treatment stability is demonstrated, in accordance with local regulations and clinical guidelines.
Severe Chronic Pain (Adults)
Methadone for Pain Management
Starting dose: 2.5–10 mg orally every 8–12 hours. The starting dose depends on the patient’s prior opioid exposure and should be at the lower end for opioid-naive or opioid-tolerant patients rotating from another opioid.
Dose titration: Increases should be made no more frequently than every 5–7 days by no more than 2.5–5 mg per dose. Because of methadone’s long half-life, rapid titration can lead to fatal accumulation.
Opioid rotation: Converting from another opioid to methadone requires specialist expertise. Standard equianalgesic tables significantly overestimate methadone dose requirements due to incomplete cross-tolerance. Generally, the calculated equianalgesic dose should be reduced by 75–90%.
Monitoring: ECG monitoring is recommended before starting methadone for pain, at 30 days, annually, and whenever the dose exceeds 100 mg daily or unexplained symptoms occur (e.g., palpitations, syncope).
Elderly Patients
Elderly patients are more susceptible to the effects of methadone due to age-related decreases in liver function, renal clearance, and respiratory reserve. Starting doses should be at the lower end of the recommended range, and dose titration should proceed more slowly. Enhanced monitoring for respiratory depression, sedation, QT prolongation, and falls is essential. A starting dose of 2.5–5 mg with careful upward titration is generally advisable.
Missed Dose
If you miss a dose of methadone, take it as soon as you remember. However, if several hours have passed and the next scheduled dose is approaching, consult your treatment team before taking the missed dose. Do not take a double dose. If you miss three or more consecutive days of methadone, do not take your usual dose without consulting your prescriber, as your tolerance may have decreased and the usual dose could cause dangerous respiratory depression. In most programs, missing three or more consecutive days requires reassessment and reinduction at a lower dose.
Overdose
Methadone overdose is a medical emergency that can be fatal. Symptoms include extreme drowsiness, slow or shallow breathing (fewer than 12 breaths per minute), blue lips and fingertips (cyanosis), pinpoint pupils, cold and clammy skin, limp muscles, slow heartbeat, loss of consciousness, and cardiac arrest. Call your local emergency number immediately. If available, administer naloxone (an opioid antagonist). Because methadone has a much longer half-life than naloxone, repeated doses of naloxone or continuous intravenous infusion may be necessary, and the patient must be monitored for at least 48–72 hours after the last methadone dose.
What Are the Side Effects of Methadone Martindale Pharma?
Like all opioid medications, methadone can cause a range of side effects. Many of the common side effects are related to its opioid agonist properties and tend to be most prominent during the induction phase of treatment. Tolerance to most side effects (with the notable exception of constipation and sweating) usually develops within the first few weeks of treatment. Patients should be informed about potential side effects and advised to report any new, persistent, or worsening symptoms to their treatment team.
Very Common (affects more than 1 in 10 people)
Frequency: >10%
- Nausea
- Vomiting (especially during induction)
- Constipation (persists throughout treatment)
- Sweating (hyperhidrosis)
- Drowsiness and sedation
- Dizziness and lightheadedness
Common (affects 1 in 10 to 1 in 100 people)
Frequency: 1–10%
- Dry mouth (xerostomia)
- Headache
- Itching (pruritus)
- Skin rash
- Loss of appetite
- Weight gain
- Difficulty sleeping (insomnia) or excessive sleepiness
- Mood changes, including euphoria and dysphoria
- Urinary retention
- Reduced libido and sexual dysfunction
- Menstrual irregularities in women
- Orthostatic hypotension (drop in blood pressure on standing)
Uncommon (affects 1 in 100 to 1 in 1,000 people)
Frequency: 0.1–1%
- QT prolongation on ECG
- Biliary spasm (pain in the upper right abdomen)
- Confusion and cognitive impairment
- Visual disturbances
- Hallucinations
- Peripheral edema (swelling of ankles/feet)
- Flushing
Rare (affects fewer than 1 in 1,000 people)
Frequency: <0.1%
- Torsades de pointes (a dangerous heart rhythm)
- Severe respiratory depression
- Anaphylaxis (severe allergic reaction)
- Seizures
- Adrenal insufficiency
- Serotonin syndrome (when combined with serotonergic drugs)
Long-term methadone maintenance therapy may be associated with additional effects including dental problems (due to dry mouth and sugar-containing oral solutions), reduced testosterone levels in men (hypogonadism), osteoporosis (related to hypogonadism), chronic constipation, and excessive sweating. These long-term effects should be discussed with your treatment team, and appropriate monitoring and management strategies should be implemented.
Contact your emergency services or go to the nearest emergency department immediately if you experience: very slow or shallow breathing, severe drowsiness from which you cannot be woken, blue or grey lips or fingertips, chest pain, fast or irregular heartbeat, fainting or near-fainting, severe allergic reaction (swelling of face, throat, difficulty breathing, severe rash or hives), or seizures.
How Should You Store Methadone Martindale Pharma?
Proper storage of methadone is critically important both for maintaining the medication’s stability and for safety reasons. Methadone is a potent opioid that can cause fatal respiratory depression in opioid-naive individuals, particularly children. Even a small amount of methadone oral solution can be lethal to a child. The following storage guidelines should be strictly observed:
- Temperature: Store at room temperature, below 25°C (77°F). Do not freeze. Protect from excessive heat.
- Light: Protect from direct light. Store in the original container with the cap tightly closed.
- Children: Keep in a safe, secure location out of the reach and sight of children. Accidental ingestion by a child is a medical emergency that can be fatal.
- Security: Methadone is a controlled substance. Store it securely to prevent theft, diversion, or accidental access by others. In many jurisdictions, take-home doses must be stored in a lockable container.
- Expiry date: Do not use after the expiry date printed on the packaging. The expiry date refers to the last day of that month.
- Disposal: Do not dispose of unused methadone in household waste or down the drain. Return any unused medication to your pharmacy or treatment clinic for safe disposal in accordance with local regulations.
Accidental ingestion of even one dose of methadone by a child or an adult who does not normally take opioids can result in a fatal overdose. If accidental ingestion is suspected, call your local emergency number or poison control center immediately. Do not wait for symptoms to appear, as respiratory depression from methadone may have a delayed onset due to its gradual absorption and long half-life.
What Does Methadone Martindale Pharma Contain?
Each milliliter of Methadone Martindale Pharma oral solution contains:
- Active substance: Methadone hydrochloride 2 mg/ml. Methadone hydrochloride is the hydrochloride salt of the racemic mixture of (R)- and (S)-methadone. The (R)-enantiomer (also known as levomethadone or L-methadone) is responsible for the majority of the opioid analgesic activity, while the (S)-enantiomer contributes primarily to the NMDA receptor antagonism and some of the cardiac effects (QT prolongation).
The oral solution formulation is specifically designed for use in opioid substitution therapy programs, where supervised consumption is standard practice. The liquid form allows for precise dose measurement and is more difficult to divert or inject compared to tablet formulations. The specific inactive ingredients (excipients) may include purified water, methyl parahydroxybenzoate (preservative), glycerol, sorbitol (sweetener), and other pharmaceutical-grade excipients. The exact composition may vary by batch and specific product license; patients should check the product packaging or consult their pharmacist for the full list of excipients, particularly if they have known allergies or intolerances to specific excipients.
Patients with fructose intolerance should be aware that some oral solution formulations may contain sorbitol. Patients with known sensitivity to preservatives should note the potential presence of methyl parahydroxybenzoate (E218), which belongs to the paraben family and can rarely cause allergic reactions (possibly delayed). If you have any allergies or intolerances, inform your prescriber and pharmacist so they can verify the suitability of this formulation for you.
Frequently Asked Questions About Methadone Martindale Pharma
Methadone Martindale Pharma is a 2 mg/ml oral solution containing methadone hydrochloride. It is primarily used for opioid substitution therapy (maintenance treatment) in adults with opioid dependence, as part of a comprehensive treatment program that includes medical, social, and psychological support. The medication helps prevent withdrawal symptoms, reduce cravings, and block the euphoric effects of illicit opioids. Methadone is also used for the management of severe chronic pain where other strong opioid analgesics have proved inadequate or are not tolerated. It is listed on the WHO Model List of Essential Medicines.
Methadone has a long and variable elimination half-life, ranging from approximately 8 to 59 hours, with an average of about 22 hours. This means methadone can remain detectable in the body for several days after the last dose. Steady-state plasma concentrations are typically reached within 3–10 days of regular dosing. The long half-life is what allows once-daily dosing in maintenance therapy but also means that dose adjustments must be made cautiously, with at least 3–5 days between increases, to avoid dangerous accumulation.
Methadone maintenance treatment is considered the standard of care for pregnant women with opioid use disorder by the WHO, ACOG, and other major medical organizations. Untreated opioid dependence during pregnancy carries significantly greater risks (miscarriage, preterm birth, low birth weight, stillbirth) than continued methadone maintenance. However, the newborn may experience neonatal abstinence syndrome (NAS) and will need monitoring after delivery. Dose adjustments may be necessary during pregnancy. The decision should always be made in consultation with both an addiction specialist and an obstetrician.
Yes, methadone overdose can be fatal. The risk is highest during treatment initiation, dose increases, and when methadone is taken with other central nervous system depressants such as benzodiazepines, alcohol, or other opioids. Symptoms of overdose include slow or shallow breathing, extreme drowsiness, cold and clammy skin, pinpoint pupils, slow heartbeat, loss of consciousness, and cardiac arrest. Methadone overdose is a medical emergency requiring immediate treatment with naloxone and emergency care. Because methadone has a much longer half-life than naloxone, repeated doses may be necessary.
Both methadone and buprenorphine are evidence-based medications for treating opioid use disorder. Methadone is a full opioid agonist that must typically be dispensed daily at a specialist clinic (at least initially), while buprenorphine is a partial opioid agonist that can often be prescribed in office-based settings. Methadone has a higher risk of respiratory depression and drug interactions, but may be more effective for patients with severe opioid dependence or those who do not respond to buprenorphine. Buprenorphine has a ceiling effect on respiratory depression, making it somewhat safer in overdose. The choice depends on individual patient factors, local regulations, and clinical judgment.
The most common side effects of methadone include nausea, vomiting, constipation, drowsiness, dizziness, dry mouth, and sweating. These effects are generally most pronounced during the initial phase of treatment and often improve as tolerance develops. Constipation tends to persist throughout treatment and may require ongoing management with laxatives and dietary modifications. Serious side effects that require immediate medical attention include difficulty breathing, chest pain, fast or irregular heartbeat, severe dizziness or fainting, and signs of allergic reaction.
References
All medical information on this page is based on peer-reviewed research, international clinical guidelines, and official drug product information. The following sources were consulted:
- 1 World Health Organization (WHO). Guidelines for the Psychosocially Assisted Pharmacological Treatment of Opioid Dependence. Geneva: WHO; 2009. Available at: who.int/publications
- 2 World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List (2023). Geneva: WHO; 2023. Methadone included as essential medicine for opioid dependence and palliative care.
- 3 Mattick RP, Breen C, Kimber J, Davoli M. Methadone maintenance therapy versus no opioid replacement therapy for opioid dependence. Cochrane Database of Systematic Reviews. 2009;(3):CD002209. doi:10.1002/14651858.CD002209.pub2
- 4 European Medicines Agency (EMA). Methadone Hydrochloride – Summary of Product Characteristics. London: EMA; 2024.
- 5 U.S. Food and Drug Administration (FDA). Methadone Hydrochloride Oral Concentrate – Prescribing Information. Silver Spring, MD: FDA; 2023. FDA Boxed Warning for respiratory depression, QT prolongation, and concomitant CNS depressant use.
- 6 British National Formulary (BNF). Methadone Hydrochloride Monograph. London: NICE; 2024. Available at: bnf.nice.org.uk
- 7 Substance Abuse and Mental Health Services Administration (SAMHSA). Federal Guidelines for Opioid Treatment Programs. HHS Publication No. (SMA) 15-4892. Rockville, MD: SAMHSA; 2015 (updated 2024).
- 8 American College of Obstetricians and Gynecologists (ACOG). Committee Opinion No. 711: Opioid Use and Opioid Use Disorder in Pregnancy. Obstetrics & Gynecology. 2017;130(2):e81–e94.
- 9 Chou R, Cruciani RA, Fiellin DA, et al. Methadone Safety: A Clinical Practice Guideline from the American Pain Society and College on Problems of Drug Dependence. The Journal of Pain. 2014;15(4):321–337. doi:10.1016/j.jpain.2014.01.494
- 10 Degenhardt L, Bucello C, Mathers B, et al. Mortality among regular or dependent users of heroin and other opioids: a systematic review and meta-analysis of cohort studies. Addiction. 2011;106(1):32–51. doi:10.1111/j.1360-0443.2010.03140.x
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, comprising licensed physicians with specialist qualifications in clinical pharmacology, addiction medicine, and pain management. All content adheres to international evidence-based guidelines and undergoes rigorous peer review.
iMedic Medical Editorial Team – Specialists in Clinical Pharmacology and Addiction Medicine with experience in opioid agonist therapy programs and evidence-based guideline development.
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