SARISOL NO. 1
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SARISOL NO. 1 (SARISOL NO. 1).
Combination analgesic and muscle relaxant; orphenadrine is a centrally acting muscle relaxant that may exert its effects via inhibition of the reticular activating system and blockade of muscarinic receptors; aspirin inhibits cyclooxygenase enzymes, reducing prostaglandin synthesis and providing analgesic and anti-inflammatory effects; caffeine is a CNS stimulant that may enhance analgesia.
| Metabolism | Orphenadrine: Hepatic metabolism (N-demethylation via CYP450 enzymes). Aspirin: Hepatic hydrolysis to salicylic acid, further conjugation (glycine, glucuronic acid). Caffeine: Hepatic metabolism via CYP1A2 (paraxanthine, theobromine, theophylline). |
| Excretion | Renal (70-80% as unchanged drug, 10-15% as glucuronide conjugate); biliary/fecal (5-10%) |
| Half-life | Terminal elimination half-life is 10-12 hours in adults with normal renal function; prolonged to 20-30 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | Approximately 85%, primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.8-1.2 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 60-70% (due to first-pass metabolism); intramuscular: 80-90%; intravenous: 100%. |
| Onset of Action | Oral: 30-60 minutes; intramuscular: 15-30 minutes; intravenous: 5-10 minutes. |
| Duration of Action | Oral: 4-6 hours; intramuscular: 4-6 hours; intravenous: 3-4 hours. Duration may be extended in hepatic impairment due to reduced clearance. |
Butalbital 50 mg, acetaminophen 300 mg, and caffeine 40 mg orally every 4 hours as needed; maximum 6 tablets per day.
| Dosage form | TABLET |
| Renal impairment | Acetaminophen: No adjustment for mild-moderate renal impairment. Severe (CrCl<30 mL/min): extend interval to every 6 hours. Butalbital: Use with caution; barbiturates may accumulate. Caffeine: No specific adjustment. |
| Liver impairment | Acetaminophen: Child-Pugh A: no adjustment; Child-Pugh B: reduce total daily dose ≤2000 mg; Child-Pugh C: contraindicated. Butalbital: caution; barbiturates may precipitate encephalopathy. Caffeine: reduce dose. |
| Pediatric use | Not recommended for use in children under 12 years of age. |
| Geriatric use | Start at lower doses; monitor for cognitive impairment and fall risk due to butalbital; acetaminophen hepatotoxicity risk if underlying liver dysfunction. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SARISOL NO. 1 (SARISOL NO. 1).
| Breastfeeding | Acetaminophen: M/P ratio 0.91-1.42, compatible. Butalbital: M/P ratio ~0.6, excreted in low amounts; risk of infant sedation and withdrawal. Caffeine: M/P ratio ~0.5-0.75, moderate infant exposure. Caution: avoid high doses, monitor infant for sedation and irritability. |
| Teratogenic Risk | SARISOL NO. 1 (butalbital, acetaminophen, caffeine) is Pregnancy Category C. First trimester: Butalbital is a barbiturate; limited human data, animal studies show teratogenicity (cleft palate) at high doses. Second/third trimester: Butalbital may cause neonatal withdrawal, respiratory depression; acetaminophen is safe at therapeutic doses; caffeine is associated with restricted fetal growth at high intake. Overall risk: potential for neural tube defects with first-trimester barbiturate use; avoid unless benefit outweighs risk. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to components, hemophilia, bleeding disorders, asthma with nasal polyps, acute gout, peptic ulcer disease, children <12 years for viral symptoms (Reye syndrome risk), glaucoma, obstructive uropathy, myasthenia gravis, concomitant use with MAOIs, severe hepatic or renal impairment.
| Precautions | Risk of Reye syndrome (children/teenagers with viral illness), salicylate toxicity, GI bleeding, CNS depression (avoid concurrent alcohol), masking of infection/signs, hypersensitivity reactions, impaired renal function, drug interactions with methotrexate, anticoagulants, NSAIDs, MAOIs, anticholinergics. |
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| Fetal Monitoring | Monitor maternal liver function (acetaminophen hepatotoxicity risk), sedation level, blood pressure and heart rate (caffeine). Fetal: ultrasonography for growth restriction (caffeine, barbiturate), nonstress test or biophysical profile in third trimester for barbiturate exposure. Neonatal: observe for withdrawal symptoms (irritability, tremors, poor feeding) for 48 hours after delivery. |
| Fertility Effects | Acetaminophen: no known impact. Caffeine: high doses may delay conception. Butalbital: may affect menstrual cycle regularity due to enzyme induction. Overall: limited data on fertility impairment. |