FIORINAL W/CODEINE
Clinical safety rating: avoid
CNS depressants including alcohol and benzodiazepines increase sedation risk Life-threatening respiratory depression may occur especially in CYP2D6 ultra-rapid metabolizers.
Codeine is a prodrug that is metabolized to morphine, which acts as a mu-opioid receptor agonist, inhibiting ascending pain pathways. Butalbital is a barbiturate that enhances GABA-A receptor activity, producing sedation. Aspirin and caffeine provide analgesic and anti-inflammatory effects via COX inhibition and adenosine receptor antagonism, respectively.
| Metabolism | Codeine is metabolized by CYP2D6 to morphine (active) and by CYP3A4 to norcodeine. Butalbital is metabolized by hepatic microsomal enzymes. Aspirin is hydrolyzed to salicylate and conjugated in the liver. Caffeine is metabolized mainly by CYP1A2. |
| Excretion | Renal elimination: codeine (90% as metabolites, 5-15% unchanged), butalbital (60-70% unchanged, remainder as metabolites), aspirin (80-100% as salicylate and metabolites, pH-dependent). Fecal: minimal (<5%). Total renal elimination accounts for >95% of dose. |
| Half-life | Codeine: 2.5-3.5 hours; Butalbital: 35-45 hours; Aspirin: 15-20 minutes (salicylate: 2-3 hours at low doses, up to 15-30 hours at high doses). Clinical context: butalbital's long half-life leads to accumulation with repeated dosing; salicylate half-life increases significantly in overdose. |
| Protein binding | Codeine: ~25% bound to albumin; Butalbital: ~45-65% bound to albumin and lipoproteins; Aspirin: 80-90% bound to albumin (salicylate: 50-80% bound). |
| Volume of Distribution | Codeine: 3-6 L/kg; Butalbital: 0.8-1.0 L/kg; Aspirin: 0.15-0.2 L/kg. Clinical meaning: codeine's large Vd indicates extensive tissue distribution; butalbital's Vd consistent with distribution in total body water; aspirin's small Vd reflects plasma and extracellular fluid binding. |
| Bioavailability | Oral: codeine ~50-90% (first-pass metabolism); butalbital ~90-100%; aspirin ~50-75% (first-pass hydrolysis to salicylate). Rectal: butalbital and aspirin suppositories have variable absorption (50-70% of oral). |
| Onset of Action | Oral: codeine 30-60 minutes, butalbital 30-60 minutes, aspirin 15-30 minutes. Peak effects: codeine 1-2 hours, butalbital 2-4 hours, aspirin 1-2 hours. |
| Duration of Action | Oral: codeine 4-6 hours, butalbital 4-6 hours (due to sedation may persist longer), aspirin 4-6 hours (antiplatelet effect >24 hours). Clinical notes: butalbital's duration contributes to daytime sedation; analgesic effect of codeine is short-lived. |
Butalbital 50 mg, acetaminophen 325 mg, caffeine 40 mg, codeine 30 mg orally every 4 hours as needed; maximum 6 capsules per day.
| Dosage form | CAPSULE |
| Renal impairment | GFR 30-50 mL/min: caution; reduce dose or extend interval. GFR <30 mL/min: avoid use due to accumulation of codeine and metabolites. |
| Liver impairment | Child-Pugh A: caution, maximum 4 capsules per day. Child-Pugh B or C: avoid use. |
| Pediatric use | Children <12 years: not recommended. Weight-based not established; avoid due to risk of respiratory depression from codeine. |
| Geriatric use | Initiate at low end of dosing, monitor for CNS depression, constipation, and falls; maximum 4 capsules per day. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
CNS depressants including alcohol and benzodiazepines increase sedation risk Life-threatening respiratory depression may occur especially in CYP2D6 ultra-rapid metabolizers.
| FDA category | Positive |
| Breastfeeding | Butalbital and codeine are excreted into breast milk. Butalbital: M/P ratio not determined, but infant exposure may cause sedation. Codeine: M/P ratio 2.5; codeine and its active metabolite morphine can be detected in milk. Risk of infant CNS depression, especially in ULTRARAPID CYP2D6 metabolizers. Avoid breastfeeding during maternal therapy. If used, monitor infant for drowsiness, difficulty breathing, poor feeding. |
■ FDA Black Box Warning
Risk of medication errors: Do not confuse Fiorinal with Fioricet. Risk of addiction, abuse, and misuse with codeine. Life-threatening respiratory depression. Accidental ingestion of even one dose of codeine, especially by children, can be fatal. Risks from concomitant use with alcohol, benzodiazepines, or other CNS depressants. Neonatal opioid withdrawal syndrome. Hepatotoxicity with aspirin use in children with viral illness (Reye's syndrome).
| Common Effects | cough |
| Serious Effects |
Hypersensitivity to any component, significant respiratory depression, acute or severe bronchial asthma, paralytic ileus, suspected surgical abdomen, bleeding disorders (hemophilia, von Willebrand disease), concomitant use with MAOIs or within 14 days, children/teenagers with viral illness (Reye's syndrome risk), pregnancy (especially third trimester) and breastfeeding (codeine), history of addiction to opioids
| Precautions | Hepatotoxicity, Reye's syndrome (children/teenagers with chickenpox or flu), respiratory depression, addiction/abuse potential, increased intracranial pressure, impaired renal function, bleeding disorders (aspirin), GI adverse effects (aspirin), risk of serotonin syndrome (codeine with serotonergic drugs), CYP2D6 ultrarapid metabolizers (codeine toxicity), withdrawal symptoms upon discontinuation, masking of symptoms of acute abdominal conditions. |
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| Teratogenic Risk |
| First trimester: Butalbital is associated with increased risk of neural tube defects and oral clefts. Codeine may cause respiratory depression and withdrawal in neonates with prolonged use. Second and third trimesters: Chronic use may lead to fetal dependence, withdrawal, and neonatal abstinence syndrome. Butalbital may cause neonatal bleeding due to vitamin K deficiency. Codeine may cause premature labor and low birth weight. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal sedation, respiratory rate, and blood pressure. Assess fetal growth and well-being with serial ultrasound in third trimester. Monitor for signs of neonatal withdrawal after birth. Check neonatal INR if butalbital used near term; vitamin K prophylaxis recommended. |
| Fertility Effects | No specific human data on fertility impairment. Codeine may cause transient decreases in sperm motility in males at high doses. Butalbital may alter menstrual cycle due to enzyme induction of sex hormones. General effect may be reduced fertility due to hormonal disruption. |