ARBLI
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ARBLI (ARBLI).
ARBLI (arbaclofen placarbil) is a prodrug of baclofen, a GABA-B receptor agonist. It acts presynaptically to inhibit excitatory neurotransmitter release and postsynaptically to reduce neuronal excitability, leading to muscle relaxation.
| Metabolism | Primarily hydrolyzed by esterases to baclofen; baclofen is minimally metabolized (mainly renal clearance of unchanged drug). |
| Excretion | Primarily biliary (>70%) and fecal elimination; renal excretion accounts for <5% of unchanged drug. |
| Half-life | Terminal elimination half-life of 26 hours (range 20-32 h), supporting once-daily dosing; prolonged in hepatic impairment. |
| Protein binding | >99% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.7 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 70% (range 60-80%); IV: 100%. |
| Onset of Action | Oral: within 1 hour; IV: within 15 minutes. |
| Duration of Action | 24 hours, allowing once-daily dosing; effect persists until drug clearance. |
10 mg orally once daily.
| Dosage form | SUSPENSION |
| Renal impairment | eGFR ≥30 mL/min/1.73 m²: no adjustment. eGFR <30 mL/min/1.73 m²: use not recommended. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B or C: not recommended. |
| Pediatric use | Not established for patients <18 years. |
| Geriatric use | No specific dose adjustment required; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ARBLI (ARBLI).
| Breastfeeding | No data on excretion in human milk. Arbaclofen is a small molecule (MW 215.68) and likely excreted into breast milk. M/P ratio unknown. Due to potential for serious adverse reactions (e.g., sedation, respiratory depression) in nursing infants, breastfeeding is not recommended during therapy. |
| Teratogenic Risk | ARBLI (arbaclofen) is not approved for use in pregnancy. No adequate and well-controlled studies in pregnant women. In animal studies, arbaclofen showed no teratogenic effects at doses up to 4 times the maximum recommended human dose based on body surface area. However, fetal toxicity (reduced fetal weight, delayed ossification) occurred at maternally toxic doses. Based on mechanism (GABAB agonist), potential risk cannot be excluded. First trimester: unknown risk; second/third trimester: possible risk of fetal harm from maternal muscle relaxation; third trimester: risk of neonatal withdrawal (hypotonia, respiratory depression) if used near term. |
■ FDA Black Box Warning
Abrupt discontinuation may precipitate withdrawal reactions including seizures, hallucinations, and life-threatening hyperthermia (similar to baclofen withdrawal).
| Serious Effects |
["Hypersensitivity to baclofen or any component of the formulation"]
| Precautions | ["Risk of withdrawal symptoms with abrupt cessation","May cause sedation and dizziness","Use caution in renal impairment","May exacerbate psychiatric disorders","Avoid with alcohol or CNS depressants"] |
| Food/Dietary | Avoid alcohol. No specific food interactions reported, but take with or without food consistently to maintain stable drug levels. |
Loading safety data…
| Fetal Monitoring | If used during pregnancy (not recommended): monitor maternal blood pressure, heart rate, and for signs of sedation or muscle weakness. Fetal monitoring: consider ultrasound for growth assessment due to potential for reduced fetal weight. Neonatal: observe for signs of withdrawal (hypotonia, poor feeding, respiratory depression) for 48 hours after delivery. |
| Fertility Effects | No human data on fertility. In animal studies, arbaclofen did not impair fertility in male or female rats at doses up to 4 times the MRHD. However, given its CNS depressant effects, theoretical risk of altered libido or menstrual irregularities. |
| Clinical Pearls |
| ARBLI (arbaclofen) is a prodrug of baclofen used for spasticity. Titrate slowly to avoid CNS depression. Monitor renal function; dose adjustment required in CrCl <60 mL/min. Avoid abrupt discontinuation due to withdrawal symptoms. Use with caution in patients with history of substance abuse due to abuse potential. |
| Patient Advice | Take exactly as prescribed; do not increase dose without consulting your doctor. · Do not stop taking abruptly; gradual dose reduction is necessary to prevent withdrawal symptoms (hallucinations, seizures, rapid heart rate). · Avoid driving or operating heavy machinery until you know how ARBLI affects you, as it may cause dizziness or drowsiness. · Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids) as they increase sedation risk. · Inform your doctor if you have kidney problems, diabetes, or a history of substance abuse. · Store at room temperature away from moisture and heat. |