BACLOFEN 2000 ug/mL Injection
Other active recalls for Baclofen (different manufacturers) — 1 · tap to view
🆔 Identity & classification
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🏷️ RxNorm drug class
This medicine belongs to the gamma-Aminobutyric Acid-ergic Agonist class.
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🏭 Manufacturer & labeler
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🩺 Clinical
- Baclofen is prescribed to reduce spasticity — the muscle stiffness, spasms, and rigidity that come with conditions like multiple sclerosis or spinal cord injury. Oral forms are als...
- What exactly is baclofen being used to treat — and will it help my pain too?
- Yes, and this is really important. Stopping baclofen suddenly — especially the pump form — can cause a dangerous withdrawal reaction: your spasticity can return much worse than bef...
- I heard you can't just stop taking baclofen — is that really true?
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
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UNII 451W47IQ8X
Sodium chloride is common table salt. It's used in medicines as a buffer to maintain proper pH, as a filler to add bulk, or to adjust the osmotic balance in liquid formulations.
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UNII 059QF0KO0R
Water is a liquid solvent that dissolves and mixes ingredients together in liquid medicines, syrups, and injections. It helps distribute the active drug evenly throughout the product.
2 inactive ingredients listed in the exact product block matched to this NDC.
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ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per each | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | $29.82 | $29.82 / 1 vial |
| Medicare drug plans payPart D · quarterly | No Part D plan price is available for this NDC in our data. | |
| Medicare Part B allowsASP · J0475 | $186.106 / J0475 unit | — |
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🧾 Billing & reimbursement
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🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Baclofen 2000 ug/mLthis 14789-0161-05 | Nexus | 1 vial | — | AP | FDA listed | — |
| Baclofen 2000 ug/mL 25021-0679-20 | Sagent | 1 vial | — | AP | FDA listed | — |
| Gablofen 2000 ug/mL 66794-0157-01 | Piramal | 20 ml | — | AP | FDA listed | — |
| Lioresal (baclofen) 70121-2503-01 | Amneal | 1 ampule | — | AP | FDA listed | — |
| Lioresal (baclofen) 70121-2505-02 | Amneal | 2 ampules | — | AP | FDA listed | — |
| Baclofen (Intrathecal) 2000 ug/mL 70511-0124-10 | MAIA | 1 vial | — | AP | FDA listed | — |
| Baclofen 2000 ug/mL 72888-0147-36 | Advagen | 1 vial | — | AP | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
Where does this data come from?
🗺️ Medicaid utilization & spend
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Reporter sex
Serious outcomes
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📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 14789-0161-05 You're viewing this | 1 VIAL in 1 CARTON (14789-161-05) / 20 mL in 1 VIAL | 2023-02-22 | Active |
🧭 About this NDC listing & data coverage
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | ✓ Available |
| HCPCS J-code billing crosswalk | ✓ Available |
| Medicaid utilization (CMS SDUD) | ✓ Available |
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📄 Full prescribing information FDA SPL
🚨 Boxed Warning ▾
BOXED WARNING WARNING: DO NOT DISCONTINUE ABRUPTLY Abrupt discontinuation of intrathecal baclofen, regardless of the cause, has resulted in sequelae that include high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity, that in rare cases has advanced to rhabdomyolysis, multiple organ-system failure and death. Prevention of abrupt discontinuation of intrathecal baclofen requires careful attention to programming and monitoring of the infusion system, refill scheduling and procedures, and pump alarms.
Patients and caregivers should be advised of the importance of keeping scheduled refill visits and should be educated on the early symptoms of baclofen withdrawal. Special attention should be given to patients at apparent risk (e.g., spinal cord injuries at T-6 or above, communication difficulties, history of withdrawal symptoms from oral or intrathecal baclofen). Consult the technical manual of the implantable infusion system for additional post-implant clinician and patient information [ see Warnings and Precautions (5.4) ].
WARNING: DO NOT DISCONTINUE ABRUPTLY See full prescribing information for complete boxed warning Abrupt discontinuation of intrathecal baclofen, regardless of the cause, has resulted in sequelae that include high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity, that in rare cases has advanced to rhabdomyolysis, multiple organ-system failure and death. Prevention of abrupt discontinuation of intrathecal baclofen requires careful attention to programming and monitoring of the infusion system, refill scheduling and procedures, and pump alarms.
Patients and caregivers should be advised of the importance of keeping scheduled refill visits and should be educated on the early symptoms of baclofen withdrawal. Special attention should be given to patients at apparent risk (e.g., spinal cord injuries at T-6 or above, communication difficulties, history of withdrawal symptoms from oral or intrathecal baclofen). Consult the technical manual of the implantable infusion system for additional post-implant clinician and patient information.
( 5.4 )
🎯 Indications and Usage ▾
1 INDICATIONS AND USAGE Baclofen injection is indicated for use in the management of severe spasticity in adult and pediatric patients age 4 years and above. Patients should first respond to a screening dose of intrathecal baclofen prior to consideration for long term infusion via an implantable pump. For spasticity of spinal cord origin, chronic infusion of baclofen injection via an implantable pump should be reserved for patients unresponsive to oral baclofen therapy, or those who experience intolerable CNS side effects at effective doses.
Patients with spasticity due to traumatic brain injury should wait at least one year after the injury before consideration of long term intrathecal baclofen therapy. Baclofen injection is intended for use by the intrathecal route in single bolus test doses (via spinal catheter or lumbar puncture) and, for chronic use, only with the Medtronic SynchroMed® II Programmable Pump or other pumps labeled for intrathecal administration of baclofen injection [see Clinical Studies (14) ] . Prior to implantation of a device for chronic intrathecal infusion of baclofen injection, patients must show a response to baclofen injection in a screening trial [see Dosage and Administration (2.2) ] .
Baclofen injection is a gamma-aminobutyric acid (GABA) ergic agonist indicated for use in the management of severe spasticity of cerebral or spinal origin in adult and pediatric patients age 4 years and above. ( 1 ) Baclofen injection should be reserved for patients unresponsive to oral baclofen therapy, or those who experience intolerable central nervous system side effects at effective doses. ( 1 ) Patients should first respond to a screening dose of intrathecal baclofen prior to consideration for long term infusion via an implantable pump.
( 1 ) Spasticity due to traumatic brain injury: wait at least one year after injury before considering baclofen injection therapy. ( 1 )
⏱️ Dosage and Administration ▾
2 DOSAGE AND ADMINISTRATION Baclofen injection is intended for use by the intrathecal route in single bolus test doses (via spinal catheter or lumbar puncture) and, for chronic use in the Medtronic SynchroMed® II Programmable Pump or other pumps labeled for intrathecal administration of baclofen injection; Refer to the pump manufacturer's manual and follow the specific instructions and precautions for programming the pump and/or refilling the reservoir. ( 2.1 ) Screening: Patients who do not respond to a 100 mcg intrathecal bolus should not be considered for an implanted pump for chronic infusion.
( 2.2 ) Dose Titration: Spasticity may be necessary to sustain upright posture and balance in locomotion or may be useful to obtain optimal function and care. ( 2.5 ) Maintenance Therapy: Titrate patients individually; Lowest dose with an optimal response should be used, generally 300 mcg/day to 800 mcg/day for spasticity of spinal cord origin and 90 mcg/day to 700 mcg/day for spasticity of cerebral origin; Titrate baclofen injection to maintain some degree of muscle tone and allow occasional spasms. ( 2.6 )
2.1Use Only in Medtronic SynchroMed® II Programmable Pump (or other pumps labeled for intrathecal administration of baclofen injection) Baclofen injection is approved only for use with the Medtronic SynchroMed ® II Programmable Pump or other pumps labeled for intrathecal administration of baclofen injection. Refer to the manufacturer’s manual for specific instructions and precautions for programming the pump and/or refilling the reservoir. It is important to select the appropriate refill kit for the pump used to administer baclofen injection.
Baclofen injection is not to be compounded with other medications.
2.2Screening Phase Prior to pump implantation and initiation of chronic infusion of baclofen injection, patients must demonstrate a positive clinical response to a baclofen injection bolus dose administered intrathecally in a screening trial. The screening trial employs baclofen injection at a concentration of 50 mcg/mL. A 1 mL syringe (50 mcg/mL) is available for use in the screening trial.
The screening procedure is as follows. An initial bolus containing 50 micrograms in a volume of 1 milliliter is administered into the intrathecal space by barbotage over a period of not less than one minute. The patient is observed over the ensuing 4 to 8 hours.
A positive response consists of a significant decrease in muscle tone and/or frequency and/or severity of spasms. If the initial response is less than desired, a second bolus injection may be administered 24 hours after the first. The second screening bolus dose consists of 75 micrograms in 1.5 milliliters.
Again, the patient should be observed for an interval of 4 to 8 hours. If the response is still inadequate, a final bolus screening dose of 100 micrograms in 2 milliliters may be administered 24 hours later. Pediatric Patients The starting screening dose for pediatric patients is the same as in adult patients, i.e., 50 mcg.
However, for very small patients, a screening dose of 25 mcg may be tried first. Patients who do not respond to a 100 mcg intrathecal bolus should not be considered candidates for an implanted pump for chronic infusion.
2.3Preparation Information Screening Use the 1 mL screening syringe only (50 mcg/mL) for bolus injection into the subarachnoid space. For a 50 mcg bolus dose, use 1 mL of the screening syringe. Use 1.5 mL of 50 mcg/mL baclofen injection for a 75 mcg bolus dose.
For the maximum screening dose of 100 mcg, use 2 mL of 50 mcg/mL baclofen injection (2 screening syringes). Maintenance The specific concentration that should be used depends upon the total daily dose required as well as the delivery rate of the pump. For patients who require concentrations other than 500 mcg/mL, 1,000 mcg/mL, or 2,000 mcg/mL, baclofen injection must be diluted with sterile preservative free Sodium Chloride for Injection, USP.
2.4 Administration Information Parenter…
💊 Dosage Forms and Strengths ▾
3 DOSAGE FORMS AND STRENGTHS Baclofen injection is available, for intrathecal use only, in: Single-dose vials of 10,000 mcg per 20 mL (500 mcg/mL) Single-dose vials of 20,000 mcg per 20 mL (1,000 mcg/mL) Single-dose vials of 40,000 mcg per 20 mL (2,000 mcg/mL) Injection: 500 mcg/mL, 1,000 mcg/mL and 2,000 mcg/mL
⛔ Contraindications ▾
4 CONTRAINDICATIONS Baclofen injection is contraindicated in patients with a hypersensitivity to baclofen. Do not use baclofen injection for intravenous, intramuscular, subcutaneous or epidural administration. Hypersensitivity to baclofen ( 4 ) Do not use baclofen injection for intravenous, intramuscular, subcutaneous or epidural administration. (4)
⚠️ Warnings and Cautions ▾
5 WARNINGS AND PRECAUTIONS Do not directly inject baclofen injection into the pump catheter access port, as this may cause a life-threatening overdose. ( 5.1 ) Potential for contamination due to non-sterile external surface of prefilled syringe. ( 5.2 ) Potentially life-threatening CNS depression, cardiovascular collapse, and/or respiratory failure; Resuscitative equipment and trained staff must be available during screening, dose titration, and refills ( 5.3 ) Overdose may cause drowsiness, lightheadedness, dizziness, somnolence, respiratory depression, seizures, rostral progression of hypotonia and loss of consciousness progressing to coma.
( 5.4 ) Possible exacerbation of psychotic disorders, schizophrenia or confusional states ( 5.6 )
5.1Risk of Life-Threatening Overdose During Pump Refills Use extreme caution when filling the Medtronic SynchroMed ® II Programmable Pump which is equipped with an injection port that allows direct access to the intrathecal catheter. Direct injection into the catheter through the catheter access port may cause a life-threatening overdose. Reservoir refilling must be performed by fully trained and qualified personnel following the directions provided by the pump manufacturer.
Carefully calculate refill intervals to prevent depletion of the reservoir, as this would result in the return of severe spasticity and possibly symptoms of withdrawal. Strict aseptic technique in filling is required to avoid bacterial contamination and serious infection. A period of observation appropriate to the clinical situation should follow each refill or manipulation of the drug reservoir.
5.2Potential for Contamination due to Non-sterile External Surface of Prefilled Syringe Although the drug solution and pathway in the baclofen injection prefilled syringes are sterile, the external surface of the prefilled syringes (all strengths, including the 50 mcg/mL strength) are non-sterile. This has the potential to lead to contamination and consequent adverse reactions. The use of baclofen injection prefilled syringe in an aseptic setting (e.g., operating room) to fill sterile intrathecal pumps prior to implantation in patients is not recommended, unless the external surface of the prefilled syringe is treated to ensure sterility.
Baclofen injection supplied in vials may be used with conventional aseptic technique to fill intrathecal pumps prior to implantation. Procedures should also be put in place while refilling implantable intrathecal pumps in an outpatient setting to avoid contamination of sterile surfaces through contact with the non-sterile exterior of the baclofen injection prefilled syringe.
5.3Prescriber, Caregiver and Patient Training and Screening Procedure/Post- Implantation Environment Baclofen injection is for use in single bolus intrathecal injections (via a catheter placed in the lumbar intrathecal space or injection by lumbar puncture) and in the implantable Medtronic SynchroMed® II Programmable Pump or other pumps labeled for intrathecal administration of baclofen injection. Because of the possibility of potentially life-threatening CNS depression, cardiovascular collapse, and/or respiratory failure, physicians must be adequately trained and educated in chronic intrathecal infusion therapy.
The pump system should not be implanted until the patient's response to bolus baclofen injection injection is adequately evaluated. Evaluation (consisting of a screening procedure) requires that baclofen injection be administered into the intrathecal space via a catheter or lumbar puncture [see Dosage and Administration (2.2) ] . Because of the risks associated with the screening procedure and the adjustment of dosage following pump implantation, these phases must be conducted in a medically supervised and adequately equipped environment following the instructions outlined in the Dosage and Administration section [see Dosage and Administration ( 2.2 and 2.5 )] .
Resuscitative equipment should be available. Follow…
🤒 Adverse Reactions ▾
6 ADVERSE REACTIONS The most common adverse reactions in patients with spasticity of spinal origin were somnolence, dizziness, nausea, hypotension, headache, convulsions and hypotonia. ( 6.1 ) The most common adverse reactions in patients with spasticity of cerebral origin were agitation, constipation, somnolence, leukocytosis, chills, urinary retention and hypotonia. ( 6.2 ) To report SUSPECTED ADVERSE REACTIONS, contact Nexus Pharmaceuticals at 1-855-642-2594 or email: [email protected] or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
6.1Spasticity of Spinal Cord Origin Most Common Adverse Reactions in Patients with Spasticity of Spinal Origin In pre- and post-marketing clinical trials, the most common adverse reactions associated with use of intrathecal baclofen which were not seen at an equivalent incidence among placebo-treated patients were: somnolence, dizziness, nausea, hypotension, headache, convulsions and hypotonia. Adverse Reactions Associated with Discontinuation of Treatment 8/474 patients with spasticity of spinal cord origin receiving long term infusion of intrathecal baclofen in pre- and post-marketing clinical studies in the U.S. discontinued treatment due to adverse reactions.
These include: pump pocket infections (3), meningitis (2), wound dehiscence (1), gynecological fibroids (1) and pump overpressurization (1) with unknown, if any, sequela. Eleven patients who developed coma secondary to overdose had their treatment temporarily suspended, but all were subsequently re-started and were not, therefore, considered to be true discontinuations. Fatalities - [see Warnings and Precautions (5.6)] .
Incidence in Controlled Trials Experience with intrathecal baclofen obtained in parallel, placebo-controlled, randomized studies provides only a limited basis for estimating the incidence of adverse reactions because the studies were of very brief duration (up to three days of infusion) and involved only a total of 63 patients. The following events occurred among the 31 patients receiving intrathecal baclofen in two randomized, placebo-controlled trials: hypotension (2), dizziness (2), headache (2), dyspnea (1). No adverse reactions were reported among the 32 patients receiving placebo in these studies.
Events Observed during the Pre- and Post-marketing Evaluation of Intrathecal Baclofen Adverse events associated with the use of intrathecal baclofen reflect experience gained with 576 patients followed prospectively in the United States. They received intrathecal baclofen for periods of one day (screening) (N=576) to over eight years (maintenance) (N=10). The usual screening bolus dose administered prior to pump implantation in these studies was typically 50 mcg.
The maintenance dose ranged from 12 mcg to 2,003 mcg per day. Because of the open, uncontrolled nature of the experience, a causal linkage between events observed and the administration of intrathecal baclofen cannot be reliably assessed in many cases and many of the adverse reactions reported are known to occur in association with the underlying conditions being treated. Nonetheless, many of the more commonly reported reactions — hypotonia, somnolence, dizziness, paresthesia, nausea/vomiting and headache — appear clearly drug-related.
Adverse experiences reported during all U.S. studies (both controlled and uncontrolled) are shown in Table 1. Eight of 474 patients who received chronic infusion via implanted pumps had adverse experiences which led to a discontinuation of long term treatment in the pre- and post-marketing studies. Table 1: Most Common (≥1%) Adverse Reactions in Patients with Spasticity of Spinal Origin in Prospectively Monitored Clinical Trials Adverse Reaction Percent N=576 Screening* Percent N=474 Titration† Percent N=430 Maintenance ‡ Hypotonia 5.4 13.5
25.3Somnolence 5.7 5.9
20.9Dizziness 1.7 1.9
7.9Paresthesia 2.4 2.1
6.7Nausea and Vomiting 1.6 2.3
5.6Headache 1.6 2.5
5.1Constipation 0.2 1.5
5.1Convulsion 0.5 1.3 4.…
🔄 Drug Interactions ▾
7 DRUG INTERACTIONS There is inadequate systematic experience with the use of intrathecal baclofen in combination with other medications to predict specific drug-drug interactions. Interactions attributed to the combined use of baclofen injection and epidural morphine include hypotension and dyspnea. Combined use with morphine: hypotension and dyspnea
👥 Use in Specific Populations ▾
8 USE IN SPECIFIC POPULATIONS Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ) Pediatric use: Safety and effectiveness in pediatric patients below the age of 4 years have not been established ( 8.4 )
8.1Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of baclofen injection in pregnant women. In animal studies, oral administration of baclofen to pregnant rats produced an increase in fetal malformations (see Data) . There are no animal data on developmental risk associated with baclofen administered via continuous intrathecal infusion.
The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Baclofen given orally to pregnant rats has been shown to increase the incidence of omphaloceles (ventral hernias) in fetuses at a dose associated with maternal toxicity.
This abnormality was not seen in mice or rabbits.
8.2Lactation Risk Summary There is insufficient information regarding levels of baclofen in milk of nursing mothers receiving baclofen injection. There are no adequate data on the effects of baclofen injection on the breastfed infant or on milk production. At recommended oral doses, baclofen is present in human milk and withdrawal symptoms can occur in breastfed infants when maternal administration of baclofen is stopped or when breastfeeding is stopped.
The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for baclofen injection and any potential adverse effects on the breastfed infant from baclofen injection or from the underlying maternal condition.
8.4Pediatric Use Children should be of sufficient body mass to accommodate the implantable pump for chronic infusion. Please consult pump manufacturer's manual for specific recommendations. Safety and effectiveness in pediatric patients below the age of 4 have not been established.
🤰 Pregnancy ▾
8.1Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of baclofen injection in pregnant women. In animal studies, oral administration of baclofen to pregnant rats produced an increase in fetal malformations (see Data) . There are no animal data on developmental risk associated with baclofen administered via continuous intrathecal infusion.
The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Baclofen given orally to pregnant rats has been shown to increase the incidence of omphaloceles (ventral hernias) in fetuses at a dose associated with maternal toxicity.
This abnormality was not seen in mice or rabbits.
🆘 Overdosage ▾
10 OVERDOSAGE Special attention must be given to recognizing the signs and symptoms of overdosage, especially during the initial screening and dose-titration phase of treatment, but also during re-introduction of baclofen injection after a period of interruption in therapy. Symptoms of Intrathecal Baclofen Overdose Drowsiness, lightheadedness, dizziness, somnolence, respiratory depression, seizures, rostral progression of hypotonia and loss of consciousness progressing to coma of up to 72 hours duration. In most cases reported, coma was reversible without sequelae after drug was discontinued.
Symptoms of intrathecal baclofen overdose were reported in a sensitive adult patient after receiving a 25 mcg intrathecal bolus. Treatment Suggestions for Overdose There is no specific antidote for treating overdoses of baclofen injection; however, the following steps should ordinarily be undertaken: 1) Residual intrathecal baclofen solution should be removed from the pump as soon as possible. 2) Patients with respiratory depression should be intubated if necessary, until the drug is eliminated.
Anecdotal reports suggest that intravenous physostigmine may reverse central side effects, notably drowsiness and respiratory depression. Caution in administering physostigmine is advised, however, because its use has been associated with the induction of seizures and bradycardia. Physostigmine Doses for Adult Patients Administer 2 mg of physostigmine intramuscularly or intravenously at a slow controlled rate of no more than 1 mg per minute.
Dosage may be repeated if life-threatening signs, such as arrhythmia, convulsions or coma occur. Physostigmine Doses for Pediatric Patients Administer 0.02 mg/kg physostigmine intramuscularly or intravenously, do not give more than 0.5 mg per minute. The dosage may be repeated at 5 to 10 minute intervals until a therapeutic effect is obtained or a maximum dose of 2 mg is attained.
Physostigmine may not be effective in reversing large overdoses and patients may need to be maintained with respiratory support. If lumbar puncture is not contraindicated, consideration should be given to withdrawing 30 to 40 mL of CSF to reduce CSF baclofen concentration.
🧬 Clinical Pharmacology ▾
12 CLINICAL PHARMACOLOGY
12.1Mechanism of Action The precise mechanism of action of baclofen as a muscle relaxant and antispasticity agent is not fully understood. Baclofen inhibits both monosynaptic and polysynaptic reflexes at the spinal level, possibly by decreasing excitatory neurotransmitter release from primary afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect. Baclofen is a structural analog of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), and may exert its effects by stimulation of the GABAB receptor subtype.
Baclofen when introduced directly into the intrathecal space permits effective CSF concentrations to be achieved with resultant plasma concentrations 100 times less than those occurring with oral administration. In people, as well as in animals, baclofen has been shown to have general CNS depressant properties as indicated by the production of sedation with tolerance, somnolence, ataxia, and respiratory and cardiovascular depression.
12.2Pharmacodynamics Intrathecal Bolus Adult Patients The onset of action is generally one-half hour to one hour after an intrathecal bolus. Peak spasmolytic effect is seen at approximately four hours after dosing and effects may last four to eight hours. Onset, peak response, and duration of action may vary with individual patients depending on the dose and severity of symptoms.
Pediatric Patients The onset, peak response and duration of action are similar to those seen in adult patients. Continuous Infusion Adult Patients Intrathecal baclofen's antispastic action is first seen at 6 to 8 hours after initiation of continuous infusion. Maximum activity is observed in 24 to 48 hours.
Pediatric Patients No additional information on continuous infusions is available for pediatric patients.
12.3Pharmacokinetics The pharmacokinetics of cerebrospinal fluid (CSF) clearance of intrathecal baclofen calculated from intrathecal bolus or continuous infusion studies approximates CSF turnover, suggesting elimination is by bulk-flow removal of CSF. Intrathecal Bolus After a bolus lumbar injection of 50 mcg or 100 mcg intrathecal baclofen in seven patients, the average CSF elimination half-life was 1.51 hours over the first four hours and the average CSF clearance was approximately 30 mL/hour. Continuous Infusion The mean CSF clearance for intrathecal baclofen was approximately 30 mL/hour in a study involving ten patients on continuous intrathecal infusion.
Concurrent plasma concentrations of baclofen during intrathecal administration are expected to be low (0 to 5 ng/mL). Limited pharmacokinetic data suggest that a lumbar-cisternal concentration gradient of about 4:1 is established along the neuroaxis during baclofen infusion. This is based upon simultaneous CSF sampling via cisternal and lumbar tap in 5 patients receiving continuous baclofen infusion at the lumbar level at doses associated with therapeutic efficacy; the interpatient variability was great.
The gradient was not altered by position. Six pediatric patients (age 8 to 18 years) receiving continuous intrathecal baclofen infusion at doses of 77 to 400 mcg/day had plasma baclofen levels near or below 10 ng/mL.
🧬 Mechanism of Action ▾
12.1Mechanism of Action The precise mechanism of action of baclofen as a muscle relaxant and antispasticity agent is not fully understood. Baclofen inhibits both monosynaptic and polysynaptic reflexes at the spinal level, possibly by decreasing excitatory neurotransmitter release from primary afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect. Baclofen is a structural analog of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), and may exert its effects by stimulation of the GABAB receptor subtype.
Baclofen when introduced directly into the intrathecal space permits effective CSF concentrations to be achieved with resultant plasma concentrations 100 times less than those occurring with oral administration. In people, as well as in animals, baclofen has been shown to have general CNS depressant properties as indicated by the production of sedation with tolerance, somnolence, ataxia, and respiratory and cardiovascular depression.
📦 How Supplied / Storage and Handling ▾
16 HOW SUPPLIED/STORAGE AND HANDLING Baclofen injection, USP is a sterile, pyrogen-free, isotonic solution available in single-dose vials of 40,000 mcg per 20 mL for intrathecal administration only. 2,000 mcg per mL NDC 14789-161-05: 20 mL Vial – 40,000 mcg per 20 mL. Baclofen injection does not contain any antioxidants, preservatives or other potentially neurotoxic additives.
Each single-dose vial is intended for single use only. Discard any unused portion. Does not require refrigeration.
Do not store above 86°F (30°C). Do not freeze. Do not heat sterilize.
📋 Description ▾
11 DESCRIPTION Baclofen injection is a muscle relaxant and antispastic. Baclofen's pharmacological class is a gamma-aminobutyric acid (GABA)ergic agonist. Baclofen's chemical name is 4-amino- 3-(4-chlorophenyl) butanoic acid, and its structural formula is: Baclofen is a white to off-white powder, with a molecular weight of 213.66.
It is slightly soluble in water, very slightly soluble in methanol and ethanol, practically insoluble in acetone and ether, soluble in 0.1N hydrochloric acid, 0.1N sodium hydroxide, and insoluble in chloroform. Baclofen injection is a sterile, pyrogen-free, isotonic solution free of antioxidants, preservatives or other potentially neurotoxic additives indicated only for intrathecal administration. The drug is stable in solution at 37°C and compatible with CSF.
Each mL of baclofen injection contains baclofen USP 500 mcg, 1,000 mcg or 2,000 mcg and sodium chloride 9 mg in Water for Injection; pH range is 5.5 to 7.5. Structural Formula
💬 Information for Patients ▾
17 PATIENT COUNSELING INFORMATION Risks Related to Sudden Withdrawal of Baclofen Injection Advise patients and caregivers that sudden withdrawal of baclofen injection, regardless of the cause, can result in serious complications that include high fever, confusion, muscle stiffness, multiple organ-system failure, and death. Inform patients that early symptoms of baclofen injection withdrawal may include increased spasticity, itching, and tingling of extremities. If baclofen injection withdrawal or a pump malfunction is suspected, patients should be brought immediately to a hospital for assessment and treatment.
Inform patients and caregivers that sudden withdrawal occurs most frequently due to a delivery problem with the catheter or the pump, or failure to refill the pump on schedule. Advise patients and their caregivers to pay careful attention to infusion system alarms. Instruct patients and caregivers that if they miss their scheduled pump refill, they should immediately contact their physician to reschedule the refill before the pump runs out of drug.
Baclofen Injection Overdose Inform patients and their caregivers that baclofen injection overdose may occur suddenly or insidiously, and that symptoms may include confusion, drowsiness, lightheadedness, dizziness, slow or shallow breathing, seizures, loss of muscle tone, loss of consciousness, and coma. If an overdose appears likely, patients should be brought immediately to a hospital for assessment and possible emptying of the pump. Operation of Automobiles and Other Dangerous Machinery Advise patients that baclofen injection may cause drowsiness, and that they should exercise caution regarding the operation of automobiles or other dangerous machinery, or activities made hazardous by decreased alertness.
Increased Risk of Drowsiness with Alcohol and Other CNS Depressants Inform patients and their caregivers that the drowsiness associated with baclofen injection use can be worsened by alcohol and other CNS depressants. Advise patients to read all medicine labels carefully, and to tell their physician about all prescription and nonprescription drugs they may use. Distributed by: Nexus Pharmaceuticals, LLC Lincolnshire, IL 60069 Made in India Revision: 12/2024 BACPI01INR02