BUTALBITAL, ACETAMINOPHEN AND CAFFEINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BUTALBITAL, ACETAMINOPHEN AND CAFFEINE (BUTALBITAL, ACETAMINOPHEN AND CAFFEINE).
Butalbital is a barbiturate that acts as a nonselective central nervous system depressant, enhancing GABAergic transmission by binding to the GABA-A receptor and increasing chloride influx, leading to sedation and anxiolysis. Acetaminophen inhibits cyclooxygenase (COX) enzymes centrally, reducing prostaglandin synthesis and providing analgesic and antipyretic effects. Caffeine is a methylxanthine that antagonizes adenosine receptors, promoting vasoconstriction and enhancing analgesic efficacy.
| Metabolism | Butalbital: primarily hepatic via hydroxylation (CYP2C19, CYP2C9, CYP3A4). Acetaminophen: hepatic via conjugation (glucuronidation, sulfation) and minor oxidation via CYP2E1. Caffeine: hepatic via CYP1A2, with N-demethylation as primary pathway. |
| Excretion | Butalbital: ~90% renal as unchanged drug and metabolites; Acetaminophen: ~85% renal as sulfate and glucuronide conjugates; Caffeine: ~1% renal unchanged, primarily hepatic metabolism. Biliary/fecal minimal (<5%). |
| Half-life | Butalbital: 35-50 hours (long-acting barbiturate, risk of accumulation with repeated dosing). Acetaminophen: 2-4 hours (normal hepatic function). Caffeine: 3-7 hours (metabolized by CYP1A2). |
| Protein binding | Butalbital: 20-30% (albumin). Acetaminophen: 10-25% (albumin). Caffeine: 25-36% (albumin). |
| Volume of Distribution | Butalbital: 0.8-1.0 L/kg (distributes widely, including CNS). Acetaminophen: 0.9-1.0 L/kg (body water). Caffeine: 0.6-0.8 L/kg (rapid distribution). |
| Bioavailability | Oral: Butalbital ~100%; Acetaminophen ~80-90%; Caffeine ~100% (rapid and complete absorption). |
| Onset of Action | Oral: Butalbital 30-60 minutes; Acetaminophen 30-60 minutes; Caffeine 15-45 minutes. Peak effect for combination: 1-2 hours. |
| Duration of Action | Butalbital: 4-6 hours (sedative effect); Acetaminophen: 4-6 hours (analgesic); Caffeine: 4-6 hours (stimulant). Combined duration: 4-6 hours. Note: Butalbital's long half-life may lead to prolonged sedation with repeated doses. |
| Molecular Weight | 238.28 |
1-2 capsules (50mg butalbital, 300mg acetaminophen, 40mg caffeine) orally every 4 hours as needed, not to exceed 6 doses per day.
| Dosage form | CAPSULE |
| Renal impairment | GFR 30-50 mL/min: Use with caution, increase dosing interval to every 6-8 hours. GFR <30 mL/min: Avoid or extend interval to every 12 hours due to acetaminophen accumulation. |
| Liver impairment | Child-Pugh Class B (moderate impairment): Reduce dose by 50% and extend interval to every 6-8 hours. Child-Pugh Class C (severe impairment): Contraindicated due to butalbital and acetaminophen metabolism. |
| Pediatric use | Children ≥12 years: Same as adult. Children <12 years: Not recommended due to butalbital risks. If used, weight-based: butalbital 1.0-1.5 mg/kg/dose, max 50 mg; acetaminophen 10-15 mg/kg/dose, max 300 mg; caffeine 1-2 mg/kg/dose, max 40 mg; orally every 4-6 hours as needed. |
| Geriatric use | Initiate at lowest effective dose (e.g., 1 capsule every 6 hours) due to increased sensitivity to butalbital (sedation, confusion) and acetaminophen hepatotoxicity risk. Monitor renal and hepatic function. |
| 1st trimester | Avoid during first trimester due to risk of neural tube defects and other congenital anomalies associated with acetaminophen and barbiturates. Use only if potential benefit outweighs risk. |
| 2nd trimester | Caution: Limited data. Butalbital may cause fetal dependence and withdrawal; acetaminophen is generally considered safer but chronic use may be associated with adverse outcomes. Use only if clearly needed. |
| 3rd trimester | Avoid in third trimester, especially near term, due to risk of neonatal withdrawal syndrome from butalbital, and potential for acetaminophen toxicity in neonate. May also prolong pregnancy and labor. |
Clinical note
Comprehensive clinical and safety monograph for BUTALBITAL, ACETAMINOPHEN AND CAFFEINE (BUTALBITAL, ACETAMINOPHEN AND CAFFEINE).
| Placental transfer | All three components cross the placenta. Butalbital demonstrates complete placental transfer with fetal serum levels similar to maternal levels. Acetaminophen readily crosses the placenta. Caffeine also crosses freely. |
| Breastfeeding |
■ FDA Black Box Warning
Butalbital can be habit-forming and may produce drug dependence (barbiturate dependence). Abrupt discontinuation may precipitate withdrawal symptoms including seizures, hallucinations, and death. Concomitant use with opioids, alcohol, or other CNS depressants may result in profound sedation, respiratory depression, coma, and death.
| Serious Effects |
Severe hepatic impairmentAcute intermittent porphyriaKnown hypersensitivity to barbiturates or acetaminophenRespiratory depressionHistory of addiction to barbiturates or sedatives
| Precautions | Hepatotoxicity risk (acetaminophen toxicity) with dose >4000 mg/day or in patients with liver disease. Risk of respiratory depression with CNS depressant co-administration. Development of tolerance, dependence, and withdrawal upon abrupt discontinuation. Use with caution in elderly, debilitated patients, and those with renal impairment. Avoid chronic use (>3 months) for headache. |
| Food/Dietary | Avoid alcohol-containing foods or beverages (increases hepatotoxicity and CNS depression). Limit caffeine-containing products (coffee, tea, cola, energy drinks) as additive effect may cause jitteriness, tachycardia, or insomnia. Grapefruit juice may inhibit CYP1A2 and increase butalbital and caffeine levels; avoid concurrent intake. |
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| Butalbital, acetaminophen, and caffeine are excreted into breast milk in small amounts. Butalbital may cause sedation and poor feeding in the infant. Acetaminophen is generally considered safe in recommended doses. Caffeine may cause irritability and poor sleep patterns. Consider alternatives during breastfeeding. |
| Lactation Rating | L3 (Moderately Safe) – use with caution, monitor infant for sedation and irritability. |
| Teratogenic Risk | First trimester: Acetaminophen and caffeine are generally considered low risk; butalbital is a barbiturate and may be associated with a small increased risk of oral clefts. Second and third trimester: Chronic high-dose butalbital may cause fetal dependence and neonatal withdrawal syndrome; acetaminophen and caffeine are considered safe at therapeutic doses. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and respiratory status; fetal heart rate monitoring during labor; watch for neonatal withdrawal if chronic use. |
| Fertility Effects | No well-documented effects on fertility; caffeine may slightly reduce fecundability at high doses; acetaminophen and butalbital are not known to impair fertility. |
| Clinical Pearls | Butalbital is a barbiturate with high abuse potential; limit prescribing to acute tension-type headache and monitor for overuse. Acetaminophen hepatotoxicity risk increases with alcohol use or pre-existing liver disease; total daily dose should not exceed 4 g (3 g in frail patients). Caffeine can exacerbate anxiety or insomnia; avoid in patients with cardiovascular conditions. Use with caution in renal impairment (butalbital accumulation) and in patients with porphyria. Pregnancy category C; avoid in breastfeeding (butalbital sedation, caffeine irritability). |
| Patient Advice | Take exactly as prescribed; do not exceed 6 tablets per day due to acetaminophen liver toxicity risk. · Avoid alcohol while taking this medication; can increase liver damage and sedation. · This medication may cause drowsiness; do not drive or operate heavy machinery until you know how it affects you. · Do not take other acetaminophen-containing products to avoid overdose. · Contact your doctor if you experience severe stomach pain, yellowing of skin or eyes, or signs of an allergic reaction. · Caffeine content may cause nervousness, trouble sleeping, or rapid heartbeat. · Report any history of substance abuse or dependence to your healthcare provider. · Store at room temperature away from moisture and heat; keep out of reach of children. |