OZOBAX DS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OZOBAX DS (OZOBAX DS).
Baclofen, a gamma-aminobutyric acid (GABA) analog, acts as an agonist at GABA-B receptors in the spinal cord, leading to decreased excitatory neurotransmitter release and reduced muscle spasticity.
| Metabolism | Hepatic metabolism via deamination; minor CYP450 involvement. |
| Excretion | Renal: 70-80% unchanged; fecal: 20-30%; biliary: <5% |
| Half-life | Terminal elimination half-life is 1.0-1.5 hours in patients with normal renal function; prolonged to 8-12 hours in moderate renal impairment (CrCl 30-50 mL/min) and up to 20-30 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | 20-30% bound to serum albumin. |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily into extracellular fluid. |
| Bioavailability | Oral: 95-100% (well absorbed); intravenous: 100%. |
| Onset of Action | Oral: 0.5-1 hour; peak effect at 1-2 hours. |
| Duration of Action | 6-8 hours based on minimum inhibitory concentration (MIC) for susceptible pathogens; prolonged in renal impairment. |
Adults: 600 mg orally twice daily; if efficacy not achieved after 2–3 weeks, may increase to 600 mg three times daily.
| Dosage form | SOLUTION |
| Renal impairment | eGFR 30–59 mL/min/1.73 m²: 300 mg twice daily. eGFR 15–29 mL/min/1.73 m²: 200 mg twice daily. eGFR <15 mL/min/1.73 m²: 200 mg once daily. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: 400 mg per day in divided doses. Child-Pugh Class C: not recommended. |
| Pediatric use | Children (6–12 years): 10–15 mg/kg per dose twice daily, max 600 mg daily. Adolescents (12–18 years): same as adult dosing. |
| Geriatric use | Start at the lower end of the dosing range (600 mg/day in divided doses) and titrate based on renal function; monitor for side effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OZOBAX DS (OZOBAX DS).
| Breastfeeding | Baclofen is excreted into human breast milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.4. The estimated infant dose from breast milk is about 0.1 mg/kg/day, which is less than 1% of the maternal weight-adjusted dose. No adverse effects in nursing infants have been reported. However, caution is advised, especially in premature infants or those with renal impairment. Monitor the infant for sedation, hypotonia, or feeding difficulties. |
| Teratogenic Risk | Ozobax DS (baclofen) is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, baclofen has been shown to increase the incidence of omphalocele (ventral hernia) in fetuses of rats given approximately 3 times the maximum human dose. In rabbits, an increased incidence of incomplete ossification of sternal centers was observed. Cases of neonatal withdrawal syndrome have been reported with chronic maternal use during the third trimester, presenting as hypertonia, tremor, and seizures. Therefore, use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Avoid use in the first trimester unless clearly needed. |
■ FDA Black Box Warning
Abrupt discontinuation may precipitate withdrawal syndrome, including severe hyperthermia, altered mental status, and muscle rigidity, which can be life-threatening. Taper slowly.
| Serious Effects |
["Hypersensitivity to baclofen or any component of the formulation","Concurrent use of tricyclic antidepressants may increase risk of respiratory depression"]
| Precautions | ["Risk of withdrawal syndrome with abrupt cessation","Dose-dependent sedation and dizziness may impair ability to drive or operate machinery","May exacerbate psychiatric disorders; use with caution in patients with depression or schizophrenia","Renal impairment requires dose adjustment","Respiratory depression risk, especially with concomitant CNS depressants"] |
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| Fetal Monitoring | Monitor maternal blood pressure, respiratory rate, and level of sedation. Assess for signs of muscle weakness or ataxia. In the fetus, monitor fetal heart rate and growth in cases of prolonged use. After delivery, monitor the neonate for signs of baclofen withdrawal (e.g., hypertonia, irritability, seizures) if the mother used the drug chronically during the third trimester. |
| Fertility Effects | In animal studies, baclofen did not impair fertility in rats at doses up to 3 times the maximum human dose. Human data are lacking. No specific effects on human fertility have been reported. However, patients with underlying conditions (e.g., multiple sclerosis) may have fertility issues unrelated to the drug. |