Amobarbital Stats & Data

Amobarbital (formerly sold as Amytal and as half of Tuinal) is an intermediate-acting barbiturate that potentiates and directly activates GABA_A receptors. The therapeutic index is narrow, and short-acting/intermediate barbiturates (incl. amobarbital) have caused fatal respiratory depression at gram-level doses; historical data place lethal doses around 2–3 g without other depressants. Because elimination is variable (reports spanning roughly 8–40 h), next-day cognitive/motor impairment is common; EU drugs data warn that impairment of judgment and fine motor skills (e.g., driving) can persist up to ~22 h after a hypnotic dose. Combining with any CNS depressant dramatically amplifies overdose risk, and there is no specific antidote for barbiturates; naloxone only helps if an opioid was also taken. In suspected overdose, do not attempt to ‘wake’ someone with stimulants; place them in the recovery position, monitor breathing, and call emergency services; clinicians may give naloxone if opioid co‑ingestion is suspected and provide airway/ventilatory support. Parenteral sodium amobarbital is alkaline; IM injections should be deep in large muscles to avoid local necrosis, and IV extravasation can cause tissue injury. Barbiturates induce CYP enzymes (notably CYP1A2, 2B6, 2C9, 3A4); this can reduce the effectiveness of many medicines including systemic hormonal contraception—use reliable non‑hormonal backup. Barbiturates can precipitate attacks in acute porphyria; avoid entirely if there is a history of porphyria. Repeated daily use for a week or more can generate severe dependence; abrupt cessation requires a medically supervised taper to prevent life‑threatening withdrawal. Barbiturates readily cross the placenta and enter breast milk; neonatal sedation/withdrawal has been reported—avoid in pregnancy/breastfeeding unless explicitly indicated and monitored.