Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PENTOTHAL vs ALLZITAL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Potentiates GABA-A receptor activity, enhancing inhibitory neurotransmission; also reduces excitatory glutamate signaling.
Allzital contains phenobarbital, a barbiturate that enhances GABA-A receptor activity by increasing the duration of chloride ion channel opening, leading to neuronal hyperpolarization and inhibition of neurotransmission.
Induction of general anesthesia,Induction of coma for increased intracranial pressure,Status epilepticus (off-label)
Sedation,Short-term treatment of insomnia,Management of seizure disorders (generalized tonic-clonic and partial seizures),Preoperative anxiety
Induction: 3-5 mg/kg IV; Maintenance: 25-75 mg IV as needed; Rectal: 25 mg/kg (max 1.5 g) for induction.
5-10 mg orally every 4-6 hours as needed for pain; not to exceed 40 mg per day.
Terminal elimination half-life is 5-12 hours (mean 8 hours) in adults. Prolonged with hepatic impairment, obesity, or high doses due to saturation of redistribution and metabolism.
Terminal elimination half-life is 4-6 hours in healthy adults; prolonged to 8-12 hours in renal impairment.
Hepatic; primarily via CYP2C9 and other CYP450 enzymes.
Primarily hepatic via CYP2C9, CYP2C19, and glucuronidation; metabolized to inactive metabolites (e.g., p-hydroxyphenobarbital) that are excreted renally.
Hepatic metabolism (approx. 80%), renal excretion of metabolites (20-30%) and unchanged drug (0.3-1%). Biliary/fecal elimination is negligible.
Renal: 70% as unchanged drug; biliary/fecal: 20% as metabolites; 10% other.
Approximately 72-86% bound, primarily to albumin (with some binding to lipoproteins).
92% bound to albumin and alpha-1-acid glycoprotein.
Vd = 1.0-2.5 L/kg (mean 1.5 L/kg). High Vd due to extensive tissue distribution, including brain and fat; correlates with high lipid solubility.
2.5-3.5 L/kg; large Vd indicates extensive tissue distribution.
IV: 100%. Rectal: approximately 60-80% (with variability). IM: approximately 60-70%. Oral: negligible due to extensive first-pass metabolism (not used clinically).
Oral: 85-90% due to first-pass metabolism; intravenous: 100%.
No specific GFR-based adjustment; use with caution in severe renal impairment due to prolonged effects.
GFR 30-50 m L/min: 50% dose reduction; GFR <30 m L/min: avoid use.
Reduce dose by 50% in Child-Pugh B and C; monitor for prolonged sedation.
Child-Pugh Class B: 50% dose reduction; Child-Pugh Class C: avoid use.
Induction: 5-6 mg/kg IV; Maintenance: 1-2 mg/kg IV as needed; Rectal: 25 mg/kg (max 1.5 g).
0.1-0.2 mg/kg orally every 4-6 hours as needed; maximum single dose 5 mg; not to exceed 20 mg per day.
Reduce induction dose to 2-3 mg/kg IV; use lower maintenance doses; increased risk of hypotension and respiratory depression.
Initiate at 2.5 mg orally every 6 hours; titrate cautiously due to increased sensitivity and risk of respiratory depression.
WARNING: RESPIRATORY DEPRESSION AND APNEA; RESUSCITATIVE EQUIPMENT AND PERSONNEL MUST BE IMMEDIATELY AVAILABLE. INTRA-ARTERIAL INJECTION MAY CAUSE ARTERIAL SPASM, THROMBOSIS, AND GANGRENE.
Risk of respiratory depression, particularly with rapid IV administration or excessive doses; co-administration with CNS depressants (e.g., opioids, alcohol) may exacerbate this effect. Use in pregnancy may cause fetal harm (teratogenic effects).
Respiratory depression, hypotension, laryngospasm, bronchospasm, cardiac arrhythmias, extravasation risk, and acute porphyria exacerbation.
Respiratory depression, CNS depression, dependence and withdrawal (taper gradually), paradoxical excitation (especially in elderly), use in hepatic or renal impairment, drug interactions with warfarin, oral contraceptives, and corticosteroids.
Hypersensitivity to barbiturates, acute porphyria, severe respiratory or cardiovascular instability, and inadequate airway management capability.
Hypersensitivity to barbiturates, severe respiratory insufficiency, history of porphyria, severe hepatic impairment, pregnancy (especially first trimester).
No specific food interactions. However, avoid alcohol for at least 24 hours due to additive CNS depression.
Avoid excessive alcohol consumption; may increase hepatotoxicity. No significant food interactions. Take with or without food; food may reduce GI upset.
PENTOTHAL (thiopental) crosses the placenta. First trimester: limited human data, animal studies show no consistent teratogenicity. Second trimester: no specific malformation risk. Third trimester: prolonged maternal administration may cause neonatal respiratory depression, hypotonia, and withdrawal. Use only if clearly needed.
Allzital (butalbital/acetaminophen/caffeine) is category C. First trimester: risk of neural tube defects increased with barbiturate exposure; avoid. Second/third trimester: barbiturate use may lead to neonatal withdrawal and coagulation defects due to vitamin K deficiency; use only if benefit outweighs risk.
Thiopental is excreted in breast milk. M/P ratio is approximately 0.4–0.8. Infant dose is low (<1% of maternal weight-adjusted dose), but caution is advised due to potential CNS depression. American Academy of Pediatrics considers compatible with breastfeeding, but monitor infant for sedation.
Butalbital and acetaminophen are excreted into breast milk in low amounts. Caffeine also enters milk. M/P ratio not established for butalbital. Use caution; monitor infant for sedation, poor feeding. American Academy of Pediatrics considers butalbital compatible with breastfeeding but avoid prolonged use.
Pregnancy may increase volume of distribution and clearance, but dosing adjustments for thiopental are not routinely recommended. Use lowest effective dose due to increased sensitivity to barbiturates. For cesarean section, standard induction doses (3-5 mg/kg IV) are used; reduced doses may be needed if combined with other sedatives.
No specific dose adjustments established for pregnancy. Pharmacokinetic changes (increased volume of distribution, hepatic metabolism) may reduce butalbital levels; clinical efficacy not well studied. Use lowest effective dose shortest duration. Acetaminophen doses remain standard (<4 g/day). Avoid caffeine >300 mg/day.
Pentothal (thiopental) is an ultra-short-acting barbiturate used for induction of anesthesia. It causes dose-dependent respiratory depression and hypotension. Administer only in a controlled setting with resuscitation equipment. Note that it is highly alkaline (p H 10-11) and extravasation causes severe tissue necrosis. Also, it is contraindicated in porphyria.
ALLZITAL is a combination analgesic containing acetaminophen and tramadol. Monitor for serotonin syndrome when used with other serotonergic drugs. Avoid in patients with severe hepatic impairment or acute alcohol intoxication. Maximum daily acetaminophen dose is 4000 mg; reduce in hepatic risk. Tramadol may lower seizure threshold; use cautiously in epilepsy. Not recommended in breastfeeding due to tramadol excretion. Adjust dose in renal impairment (Cr Cl <30 m L/min: extended interval). Discontinue gradually to avoid withdrawal.
You will receive this medication only under the supervision of an anesthesiologist.,It will cause you to fall asleep quickly and you may feel drowsy for several hours after the procedure.,Do not drive or operate machinery for at least 24 hours after receiving this medication.,Inform your doctor if you have a history of porphyria, liver disease, or allergies to barbiturates.,You may experience a bad taste or cough upon injection.
Do not exceed 8 tablets per day due to acetaminophen liver risk.,Avoid alcohol and other acetaminophen-containing products.,May cause dizziness or drowsiness; avoid driving until effect known.,Report signs of serotonin syndrome (agitation, hallucinations, rapid heart rate).,Do not stop suddenly; taper to prevent withdrawal symptoms.,Store at room temperature away from moisture.,Use only as prescribed; risk of dependence with tramadol.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PENTOTHAL vs ALLZITAL, answered by our medical review team.
PENTOTHAL is a Barbiturate Anesthetic that works by Potentiates GABA-A receptor activity, enhancing inhibitory neurotransmission; also reduces excitatory glutamate signaling.. ALLZITAL is a Barbiturate Analgesic Combination that works by Allzital contains phenobarbital, a barbiturate that enhances GABA-A receptor activity by increasing the duration of chloride ion channel opening, leading to neuronal hyperpolarization and inhibition of neurotransmission.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PENTOTHAL and ALLZITAL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PENTOTHAL is: Induction: 3-5 mg/kg IV; Maintenance: 25-75 mg IV as needed; Rectal: 25 mg/kg (max 1.5 g) for induction.. The standard adult dose of ALLZITAL is: 5-10 mg orally every 4-6 hours as needed for pain; not to exceed 40 mg per day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PENTOTHAL and ALLZITAL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PENTOTHAL is classified as Category C. PENTOTHAL (thiopental) crosses the placenta. First trimester: limited human data, animal studies show no consistent teratogenicity. Second trimester: no specific malformation risk.. ALLZITAL is classified as Category C. Allzital (butalbital/acetaminophen/caffeine) is category C. First trimester: risk of neural tube defects increased with barbiturate exposure; avoid. Second/third trimester: barbitu. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.