Baclofen Sintetica: Intrathecal Infusion for Severe Spasticity
Centrally acting muscle relaxant delivered directly into the spinal fluid
Baclofen Sintetica is a prescription intrathecal infusion solution containing baclofen, a centrally acting muscle relaxant that works as a GABA-B receptor agonist. It is used to treat severe chronic spasticity of spinal or cerebral origin in patients who have not responded adequately to oral antispasmodic medications. The medication is delivered directly into the cerebrospinal fluid through a surgically implanted programmable infusion pump, allowing effective symptom control at doses far lower than those required by oral administration.
Quick Facts
Key Takeaways
- Baclofen Sintetica is an intrathecal solution used for severe spasticity when oral treatments have failed, delivered via a surgically implanted pump.
- It acts as a GABA-B receptor agonist in the spinal cord, reducing muscle tone and spasms at doses approximately 100 times lower than oral baclofen.
- Abrupt withdrawal of intrathecal baclofen can be life-threatening, causing high fever, seizures, and potentially organ failure — never stop suddenly.
- Common side effects include drowsiness, dizziness, headache, and muscle weakness; most are dose-dependent and manageable.
- Treatment requires ongoing specialist supervision with regular pump refills and dosage adjustments every 1–3 months.
What Is Baclofen Sintetica and What Is It Used For?
Baclofen Sintetica contains the active substance baclofen, which belongs to a class of medications known as centrally acting muscle relaxants. Specifically, baclofen is a structural analogue of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and acts primarily at GABA-B receptors located in the dorsal horn of the spinal cord. By activating these receptors, baclofen inhibits both monosynaptic and polysynaptic spinal reflexes, resulting in decreased muscle tone, reduced frequency and severity of muscle spasms, and improved range of motion.
The intrathecal route of administration — meaning the drug is delivered directly into the fluid surrounding the spinal cord — is what distinguishes Baclofen Sintetica from standard oral baclofen tablets. When given intrathecally, baclofen bypasses the blood-brain barrier entirely and achieves therapeutic concentrations in the cerebrospinal fluid (CSF) at doses approximately 100 times smaller than would be needed orally. This approach dramatically reduces systemic side effects such as sedation and cognitive impairment that commonly limit the usefulness of oral baclofen at higher doses.
Baclofen Sintetica is indicated for the treatment of severe chronic spasticity arising from two principal categories:
- Spinal origin: Spasticity resulting from spinal cord injury, multiple sclerosis (MS), spinal cord tumours, transverse myelitis, or degenerative spinal conditions where spasticity significantly impairs mobility, causes pain, or interferes with activities of daily living.
- Cerebral origin: Spasticity associated with cerebral palsy, traumatic brain injury, stroke, or other brain-related conditions, particularly when spasticity is generalized and severe.
Before intrathecal baclofen therapy is initiated, patients must first have demonstrated an inadequate response to maximum tolerated doses of oral antispasmodic agents, including oral baclofen, tizanidine, and dantrolene, either individually or in combination. Additionally, patients must pass a screening trial where a single intrathecal bolus dose of baclofen (typically 25–100 micrograms) is administered via lumbar puncture to confirm that they respond favourably to the drug before committing to pump implantation surgery.
The intrathecal delivery system consists of a programmable infusion pump, typically implanted subcutaneously in the abdominal wall, connected to a catheter that is threaded into the intrathecal space. The pump reservoir is refilled at regular intervals (every 1–3 months depending on dose and concentration) by a healthcare professional using a sterile percutaneous technique. The pump is programmed externally to deliver a precise and continuous infusion rate, which can be adjusted to meet changing clinical needs.
What Should You Know Before Taking Baclofen Sintetica?
Contraindications
Baclofen Sintetica must not be used in the following circumstances:
- Hypersensitivity to baclofen or any of the excipients in the formulation.
- Untreated local or systemic infections, as intrathecal drug delivery involves an implanted device and catheter that could serve as a nidus for infection.
- Uncontrolled epilepsy, since lowering spasticity may unmask seizure activity in susceptible individuals, and baclofen can lower the seizure threshold.
- Patients in whom spasticity is used functionally to maintain upright posture or balance during locomotion — removing this tone could worsen mobility.
Warnings and Precautions
Abrupt discontinuation of intrathecal baclofen, whether due to pump malfunction, catheter dislodgement, or failure to refill the pump reservoir, can cause a potentially fatal withdrawal syndrome. Symptoms include high fever (hyperthermia), altered mental status, exaggerated rebound spasticity progressing to rhabdomyolysis, disseminated intravascular coagulation, multi-organ failure, and death. Any patient or caregiver must be educated to recognise early signs of withdrawal and to seek emergency medical attention immediately.
Additional precautions and special situations include:
- Drowsiness and sedation: Patients may experience significant sedation, especially during dose titration. Ability to drive or operate machinery may be impaired.
- Autonomic dysreflexia: In patients with spinal cord lesions above T6, changes in spasticity management can precipitate autonomic dysreflexia. Close monitoring is essential.
- Respiratory depression: High doses of intrathecal baclofen can depress respiratory drive, particularly in patients with pre-existing pulmonary disease or concomitant use of other CNS depressants.
- Urinary retention: Baclofen may worsen pre-existing bladder dysfunction. Patients with neurogenic bladder should be monitored closely.
- Psychiatric effects: Confusion, hallucinations, depression, and mood changes have been reported, particularly during dose adjustments.
- Renal impairment: Although intrathecal delivery reduces systemic exposure, caution is advised in patients with severe renal impairment, as baclofen is partially excreted renally.
Pregnancy and Breastfeeding
There are limited data on the use of intrathecal baclofen during pregnancy. Animal studies have shown reproductive toxicity at high systemic doses, including increased incidence of omphalocele (abdominal wall defects) in rats. Baclofen Sintetica should only be used during pregnancy if the potential benefit to the mother justifies the potential risk to the foetus. Women of childbearing potential should discuss contraceptive options with their physician.
Baclofen is excreted in breast milk following oral administration. Although intrathecal administration results in much lower systemic concentrations, a decision must be made whether to discontinue breastfeeding or to discontinue therapy, taking into account the importance of the drug to the mother. The European Medicines Agency (EMA) and the FDA both recommend caution.
How Does Baclofen Sintetica Interact with Other Drugs?
Although the intrathecal route of administration results in lower systemic drug levels compared to oral dosing, clinically significant drug interactions can still occur. The most important interactions involve agents that share pharmacological effects with baclofen, particularly CNS depression and cardiovascular effects. Healthcare professionals should conduct a thorough medication review before initiating intrathecal baclofen therapy and at every follow-up visit.
Major Interactions
| Drug / Class | Interaction | Clinical Significance |
|---|---|---|
| Opioid analgesics (morphine, fentanyl, oxycodone) | Additive CNS and respiratory depression | High risk — may require dose reduction of either agent; close respiratory monitoring |
| Benzodiazepines (diazepam, clonazepam, midazolam) | Enhanced sedation and respiratory depression | High risk — use lowest effective doses and monitor; risk of profound sedation |
| Tricyclic antidepressants (amitriptyline, nortriptyline) | Potentiation of muscle relaxant effect and sedation | Moderate risk — may require dose adjustments; monitor for excessive hypotonia |
| MAO inhibitors | Unpredictable potentiation of baclofen effects | High risk — avoid concomitant use or use with extreme caution |
| Antihypertensive agents (ACE inhibitors, beta-blockers, diuretics) | Additive blood pressure lowering effect | Moderate risk — monitor blood pressure; adjust antihypertensive dosing as needed |
Minor Interactions
| Drug / Class | Interaction | Clinical Significance |
|---|---|---|
| Levodopa/Carbidopa | May reduce anti-parkinsonian effect; confusion and hallucinations reported | Low to moderate risk — monitor neurological status |
| Lithium | Increased risk of hyperkinetic symptoms | Low risk — monitor for dyskinesia |
| NSAIDs (ibuprofen, naproxen) | Potential reduction of renal baclofen clearance | Low risk — limited systemic exposure with intrathecal route |
| Alcohol | Additive CNS depression and impaired motor function | Moderate risk — patients should be advised to avoid or limit alcohol |
Patients receiving intrathecal baclofen who require general anaesthesia should inform their anaesthetist. The interaction between intrathecal baclofen and anaesthetic agents can lead to unpredictable cardiovascular responses and enhanced neuromuscular blockade. Pump settings may need to be adjusted perioperatively.
What Is the Correct Dosage of Baclofen Sintetica?
Intrathecal baclofen dosing follows a three-phase approach: screening, post-implantation dose titration, and long-term maintenance. All dosing decisions must be made by a physician experienced in intrathecal drug delivery. The dosing information below reflects international guidelines from the EMA, FDA, and published clinical literature.
Screening Phase
Before pump implantation, patients undergo a screening trial to confirm responsiveness to intrathecal baclofen. A single bolus dose is administered via lumbar puncture:
Screening Trial Protocol
- Initial test dose: 25–50 micrograms as a single intrathecal bolus injection.
- Observation period: 4–8 hours following injection, with assessment of muscle tone (Ashworth scale), spasm frequency, and functional improvement.
- Dose escalation: If the initial dose produces an insufficient response, a second trial may be performed 24 hours later at 75 micrograms, and if needed, a third at 100 micrograms.
- Positive response: A clinically significant reduction in muscle tone or spasm frequency/severity lasting at least 4 hours qualifies the patient for pump implantation.
Adults
| Phase | Dose Range | Notes |
|---|---|---|
| Initial (post-implant) | Typically double the screening dose, divided over 24 hours | Spinal spasticity: start low; cerebral spasticity may require higher starting doses |
| Titration (weeks 1–12) | Increase by 10–30% per adjustment, no more frequently than every 24 hours | Aim for optimal tone reduction with minimal side effects |
| Maintenance (spinal origin) | 12–2,000 mcg/day (typical: 300–800 mcg/day) | Most patients stabilise within 6 months; reassess periodically |
| Maintenance (cerebral origin) | 22–1,400 mcg/day (typical: 90–700 mcg/day) | Cerebral palsy and stroke patients may need different titration schedules |
Children (4 years and older)
Intrathecal baclofen is approved for use in children aged 4 years and older, primarily for severe spasticity of cerebral origin (such as cerebral palsy). Paediatric dosing follows the same general principles as adult dosing but requires even more cautious titration:
Paediatric Dosing
- Screening dose: 25–50 micrograms (children weighing less than 25 kg should start at 25 mcg).
- Initial post-implant dose: Double the effective screening dose, delivered continuously over 24 hours.
- Titration: Increase by 5–15% per adjustment, no more frequently than every 24 hours.
- Typical maintenance: 24–1,199 mcg/day; most children stabilise at 100–300 mcg/day.
Elderly
There is limited specific data on intrathecal baclofen use in elderly patients. However, older adults may be more sensitive to the CNS-depressant effects of baclofen and are at higher risk of falls related to muscle weakness. Dose titration should proceed more slowly, with careful attention to sedation, blood pressure changes, and bladder function. Starting doses at the lower end of the recommended range are advised, and the interval between dose adjustments should be extended.
Missed Dose
Because intrathecal baclofen is delivered continuously via an implanted pump, the concept of a “missed dose” does not apply in the traditional sense. However, failure to attend scheduled pump refill appointments can result in the reservoir running empty, which constitutes an abrupt withdrawal situation. Patients and caregivers must be educated about the critical importance of keeping all pump refill appointments. If a refill appointment is missed, the patient or caregiver should contact their healthcare team immediately to arrange an urgent refill.
Overdose
Signs of intrathecal baclofen overdose include excessive drowsiness progressing to coma, respiratory depression, seizures, rostral progression of hypotonia, and cardiovascular collapse. Overdose can result from pump programming errors, catheter migration, or accidental bolus delivery. Treatment is primarily supportive: maintain airway and ventilation, provide intensive monitoring in an ICU setting, and reduce or stop the intrathecal infusion immediately. Physostigmine has been used as a specific antagonist in some cases, although its use remains off-label and should be guided by a toxicologist or intensivist.
What Are the Side Effects of Baclofen Sintetica?
Side effects of intrathecal baclofen can be categorised by their frequency of occurrence. The following classification is based on data from clinical trials, post-marketing surveillance, and international regulatory databases (EMA, FDA). Many of these adverse effects are dose-related and can be managed by adjusting the infusion rate. Patients should be counselled to report any new or changing symptoms promptly.
Very Common
- Drowsiness and sedation
- Muscle weakness (hypotonia)
- Dizziness
- Nausea
- Headache
Common
- Urinary retention or incontinence
- Constipation
- Hypotension (low blood pressure)
- Insomnia or sleep disturbances
- Confusion or disorientation
- Vomiting
- Fatigue and asthenia
- Paraesthesia (tingling or numbness)
- Blurred vision
- Speech disturbance (dysarthria)
Uncommon
- Respiratory depression or hypoventilation
- Seizures
- Hallucinations
- Depression or suicidal ideation
- Dry mouth
- Hypothermia
- Deep vein thrombosis
- Dysphagia (difficulty swallowing)
Rare
- Catheter-related complications (kinking, disconnection, migration)
- Pump pocket infection or meningitis
- Intrathecal granuloma at catheter tip
- Serotonin syndrome (with concomitant serotonergic drugs)
- Rhabdomyolysis (typically associated with withdrawal)
In addition to pharmacological side effects, patients should be aware of potential complications related to the intrathecal delivery system itself. These include surgical site infections, catheter migration or breakage, pump pocket seroma, cerebrospinal fluid leakage following catheter placement, and post-lumbar puncture headache. Regular follow-up appointments with the treatment team are essential for monitoring both drug effects and device function.
Long-term intrathecal baclofen therapy has been associated with the development of tolerance in some patients, requiring gradual dose increases over time. However, many patients maintain stable doses for years. If tolerance develops, a “drug holiday” (brief temporary reduction or cessation under close medical supervision) can sometimes restore sensitivity, although this carries the risk of withdrawal and should only be performed in a hospital setting.
Contact your healthcare team or seek emergency medical attention immediately if you experience: sudden return of severe spasticity (may indicate pump malfunction or empty reservoir), high fever, altered consciousness, breathing difficulties, seizures, or signs of wound infection around the pump site (redness, swelling, discharge).
How Should You Store Baclofen Sintetica?
Baclofen Sintetica solution for infusion should be stored under controlled conditions to maintain pharmaceutical stability and sterility. The following storage guidelines apply to the unopened product held by the healthcare facility prior to pump refill procedures:
- Temperature: Store at 15–30°C (59–86°F). Do not refrigerate or freeze, as extreme temperatures can affect the chemical stability of the solution.
- Light protection: Keep ampoules in the original outer carton to protect from light. Baclofen solution may degrade when exposed to prolonged light exposure.
- Sterility: The solution is intended for single use only. Once an ampoule is opened, the contents should be used immediately. Any remaining unused solution must be discarded in accordance with local regulations for pharmaceutical waste.
- Shelf life: Do not use after the expiry date printed on the ampoule and outer carton. The expiry date refers to the last day of that month.
- Inspection: Before use, visually inspect the solution. It should be a clear, colourless solution free from particulate matter. Do not use if the solution appears discoloured, cloudy, or contains particles.
Once the solution has been transferred into the implanted pump reservoir, its stability within the pump environment has been validated under conditions typical of body temperature (approximately 37°C). Pump manufacturers and drug labelling specify the maximum reservoir fill interval based on stability data. Patients should follow the refill schedule prescribed by their healthcare team to ensure both drug potency and pump function are maintained.
What Does Baclofen Sintetica Contain?
Baclofen Sintetica is formulated as a sterile, preservative-free, isotonic solution intended exclusively for intrathecal administration. The precise composition is as follows:
- Active substance: Baclofen 0.5 mg per ml (500 micrograms/ml).
- Excipients: Sodium chloride (for isotonicity), water for injections (solvent).
The solution is formulated at a physiological pH and osmolality to minimise irritation to the meninges and neural tissue. The absence of preservatives (such as benzyl alcohol or parabens) is critical for intrathecal formulations, as preservatives can be neurotoxic when administered directly into the cerebrospinal fluid. This preservative-free formulation ensures compatibility with long-term intrathecal delivery via implantable pumps.
Baclofen itself is a white to off-white crystalline powder that is slightly soluble in water. Its chemical name is (RS)-4-amino-3-(4-chlorophenyl)butanoic acid. It has a molecular weight of 213.66 g/mol and exists as a racemic mixture, with the R-enantiomer being the pharmacologically active form at GABA-B receptors. The intrathecal formulation is supplied in glass ampoules of various fill volumes depending on the strength and presentation.
Frequently Asked Questions About Baclofen Sintetica
Baclofen Sintetica is used to treat severe chronic spasticity of spinal or cerebral origin in patients who have not responded adequately to oral antispasmodic medications. Conditions treated include spasticity from multiple sclerosis, spinal cord injury, cerebral palsy, stroke, and traumatic brain injury. It is delivered directly into the cerebrospinal fluid via a surgically implanted programmable pump.
The pump implantation is a surgical procedure performed under general anaesthesia. A small programmable pump (roughly the size of a hockey puck) is placed in a pocket created under the skin of the abdomen. A thin catheter is threaded from the pump, tunnelled under the skin, and inserted into the intrathecal space of the spinal canal. The procedure typically takes 1–2 hours, and patients usually stay in hospital for 2–5 days afterwards for monitoring and initial dose titration.
If the pump reservoir runs empty, intrathecal baclofen delivery stops abruptly, which can trigger a life-threatening withdrawal syndrome. Symptoms include high fever, altered mental status, severe rebound spasticity, muscle rigidity, and in extreme cases, rhabdomyolysis and organ failure. It is critically important to attend all scheduled pump refill appointments. Modern pumps have low-reservoir alarms, but patients should also be aware of their refill schedule and contact their clinic if an appointment is missed.
Many modern intrathecal baclofen pumps are conditionally MRI-compatible, meaning MRI scans can be performed under specific conditions (such as certain field strengths and body regions). However, the pump must be interrogated and potentially stopped before the MRI, and reprogrammed afterwards. Always inform the MRI department that you have an implanted drug pump. Your intrathecal baclofen team should be consulted before any MRI scan to confirm safety protocols for your specific pump model.
Pump refill frequency depends on the prescribed dose and the pump reservoir volume. Most patients require a refill every 1 to 3 months. During a refill visit, a healthcare professional uses a sterile needle to access the pump reservoir through the skin and replaces the medication. The procedure takes approximately 30 minutes and is performed in an outpatient clinic. The pump battery typically lasts 5–7 years, after which the pump must be surgically replaced.
Yes, intrathecal baclofen is approved for children aged 4 years and older with severe spasticity of cerebral origin, most commonly cerebral palsy. Paediatric patients benefit from the same advantages as adults — effective spasticity reduction with lower systemic side effects. However, dosing must be carefully titrated by a specialist experienced in paediatric intrathecal therapy, and the pump size relative to the child's body must be considered during surgical planning.
All information is based on international medical guidelines and peer-reviewed research: the European Medicines Agency (EMA) Summary of Product Characteristics, the FDA-approved prescribing information, the British National Formulary (BNF), WHO Model List of Essential Medicines, Cochrane systematic reviews on intrathecal baclofen for spasticity, and published clinical guidelines from the American Academy of Neurology (AAN). All medical claims follow the GRADE evidence framework with evidence level 1A where available.
References
- European Medicines Agency (EMA). Summary of Product Characteristics: Baclofen intrathecal solution for infusion. Accessed January 2026.
- U.S. Food and Drug Administration (FDA). Prescribing Information: Baclofen Injection (intrathecal). Reference ID: 4876112.
- Dario A, Tomei G. A benefit-risk assessment of baclofen in severe spinal spasticity. Drug Safety. 2004;27(11):799–818. doi:10.2165/00002018-200427110-00004
- Coffey RJ, Edgar TS, Francisco GE, et al. Abrupt withdrawal from intrathecal baclofen: recognition and management of a potentially life-threatening syndrome. Archives of Physical Medicine and Rehabilitation. 2002;83(6):735–741. doi:10.1053/apmr.2002.32820
- Boster AL, Adair RL, Gooch JL, et al. Best practices for intrathecal baclofen therapy: dosing and long-term management. Neuromodulation. 2016;19(6):623–631. doi:10.1111/ner.12388
- World Health Organization (WHO). Model List of Essential Medicines, 23rd list. Geneva: WHO; 2023.
- National Institute for Health and Care Excellence (NICE). Spasticity in under 19s: management (CG145). Updated 2016.
- Cochrane Database of Systematic Reviews. Intrathecal baclofen for spasticity of cerebral origin. 2019. doi:10.1002/14651858.CD004552.pub3
- British National Formulary (BNF). Baclofen — intrathecal use. Accessed January 2026.
- American Academy of Neurology (AAN). Practice guideline update: pharmacologic treatment of spasticity in adults. Neurology. 2023;100(3):e291–e308.
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, comprising licensed specialist physicians with expertise in neurology, pharmacology, and rehabilitation medicine. All content follows international medical guidelines (WHO, EMA, FDA, BNF) and adheres to the GRADE evidence framework.
iMedic Medical Editorial Team — Specialists in neurology and clinical pharmacology with documented academic background and clinical experience in spasticity management.
iMedic Medical Review Board — Independent panel of medical experts who review all content for accuracy, completeness, and adherence to current evidence-based guidelines.
Conflict of interest: None. iMedic receives no commercial funding. All content is editorially independent with no pharmaceutical company sponsorship or advertising.
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