Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, Oral, as sodium:
Seconal: 100 mg [contains fd&c yellow #10 (quinoline yellow)]
Pharmacology
Mechanism of Action
Depresses CNS activity by binding to barbiturate site at GABA-receptor complex enhancing GABA activity, depressing reticular activity system; higher doses may be gabamimetic
Pharmacokinetics/Pharmacodynamics
Absorption
Oral: Well absorbed (90%)
Distribution
Vd: Adults: 1.5 L/kg
Metabolism
Hepatic, by microsomal enzyme system
Excretion
Urine (as inactive metabolites, small amounts as unchanged drug)
Onset of Action
Onset of hypnosis: Oral: 10 to 15 minutes
Time to Peak
Serum concentration: Oral: Within 2 to 4 hours
Duration of Action
Hypnosis: Oral: 3 to 4 hours with 100 mg dose
Half-Life Elimination
Children: 2 to 13 years: 2.7 to 13.5 hours
Adults: 15 to 40 hours, mean: 28 hours
Protein Binding
45% to 60%
Use: Labeled Indications
See Use: Unsupported.
Contraindications
Hypersensitivity to barbiturates or any component of the formulation; marked hepatic impairment; dyspnea or airway obstruction; porphyria
Dosage and Administration
Dosing: Adult
Use of secobarbital is either no longer recommended or has been supplanted by other more contemporary agents; dosing is not provided.
Dosing: Geriatric
Avoid use (Beers Criteria [AGS 2019]).
Dosing: Pediatric
Preoperative sedation: Note: Use has been replaced with other agents. Children and Adolescents: Oral: 2 to 6 mg/kg/dose administered 1 to 2 hours before surgery; maximum dose: 100 mg/dose
Storage
Store at controlled room temperature of 20°C to 25°C (68°F to 77°F).
Drug Interactions
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination
Beta-Blockers: Barbiturates may decrease the serum concentration of Beta-Blockers. Exceptions: Atenolol; Levobunolol; Metipranolol; Nadolol. Monitor therapy
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification
Blood Pressure Lowering Agents: Barbiturates may enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Consider therapy modification
Calcium Channel Blockers: Barbiturates may increase the metabolism of Calcium Channel Blockers. Management: Monitor for decreased therapeutic effects of calcium channel blockers with concomitant barbiturate therapy. Calcium channel blocker dose adjustments may be necessary. Nimodipine Canadian labeling contraindicates concomitant use with phenobarbital. Exceptions: Clevidipine. Monitor therapy
Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Chloramphenicol (Systemic): May decrease the metabolism of Barbiturates. Barbiturates may increase the metabolism of Chloramphenicol (Systemic). Consider therapy modification
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy
CycloSPORINE (Systemic): Barbiturates may increase the metabolism of CycloSPORINE (Systemic). Consider therapy modification
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Doxycycline: Barbiturates may decrease the serum concentration of Doxycycline. Consider therapy modification
Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy
Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Consider therapy modification
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Estrogen Derivatives (Contraceptive): Barbiturates may diminish the therapeutic effect of Estrogen Derivatives (Contraceptive). Contraceptive failure is possible. Management: Use of a non-hormonal contraceptive is recommended. Consider therapy modification
Felbamate: May increase the serum concentration of Barbiturates. Barbiturates may decrease the serum concentration of Felbamate. Management: Monitor for elevated barbiturate concentrations/toxicity if felbamate is initiated/dose increased, or reduced concentrations/effects if felbamate is discontinued/dose decreased. Refer to phenobarbital dosing guidelines for patients receiving that agent. Monitor therapy
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification
Griseofulvin: Barbiturates may decrease the serum concentration of Griseofulvin. Monitor therapy
Hemin: Barbiturates may diminish the therapeutic effect of Hemin. Avoid combination
HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Avoid concomitant use of hydrocodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of Barbiturates. Management: Consider a decrease in the barbiturate dose, as appropriate, when used together with hydroxyzine. With concurrent use, monitor patients closely for excessive response to the combination. Consider therapy modification
Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
LamoTRIgine: Barbiturates may decrease the serum concentration of LamoTRIgine. Management: See lamotrigine prescribing information for specific age-dependent dosing guidelines regarding concurrent use with a barbiturate, as well as for adjusting lamotrigine dosing if concurrent barbiturate therapy is discontinued. Consider therapy modification
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Consider therapy modification
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification
Methoxyflurane: Barbiturates may enhance the nephrotoxic effect of Methoxyflurane. Barbiturates may increase the metabolism of Methoxyflurane. Avoid combination
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy
Mianserin: May enhance the CNS depressant effect of Barbiturates. Mianserin may diminish the therapeutic effect of Barbiturates. Barbiturates may decrease the serum concentration of Mianserin. Avoid combination
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease the serum concentration of Barbiturates. Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Monitor therapy
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy
Primidone: May enhance the adverse/toxic effect of Barbiturates. Primidone is converted to phenobarbital, and thus becomes additive with existing barbiturate therapy. Monitor therapy
Progestins (Contraceptive): Barbiturates may diminish the therapeutic effect of Progestins (Contraceptive). Contraceptive failure is possible. Management: Use of alternative, nonhormonal contraceptives is recommended. Consider therapy modification
Propacetamol: Barbiturates may increase the metabolism of Propacetamol. This may 1) diminish the desired effects of propacetamol; and 2) increase the risk of liver damage. Monitor therapy
Pyridoxine: May increase the metabolism of Barbiturates. Apparent in high pyridoxine doses (eg, 200 mg/day) Monitor therapy
Rifamycin Derivatives: May increase the metabolism of Barbiturates. Monitor therapy
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy
Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy
Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification
Somatostatin Acetate: May enhance the adverse/toxic effect of Barbiturates. Specifically, Somatostatin Acetate may enhance or prolong Barbiturate effects, including sedative effects. Avoid combination
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification
Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Avoid concomitant use of tapentadol and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Teniposide: Barbiturates may decrease the serum concentration of Teniposide. Management: Consider alternatives to combined treatment with barbiturates and teniposide due to the potential for decreased teniposide concentrations. If the combination cannot be avoided, monitor teniposide response closely. Consider therapy modification
Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Tetrahydrocannabinol and Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination
Theophylline Derivatives: Barbiturates may decrease the serum concentration of Theophylline Derivatives. Exceptions: Dyphylline. Monitor therapy
Tricyclic Antidepressants: Barbiturates may increase the metabolism of Tricyclic Antidepressants. Consider therapy modification
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Ulipristal: Barbiturates may decrease the serum concentration of Ulipristal. Avoid combination
Valproate Products: May increase the serum concentration of Barbiturates. Barbiturates may decrease the serum concentration of Valproate Products. Monitor therapy
Vitamin K Antagonists (eg, warfarin): Barbiturates may increase the metabolism of Vitamin K Antagonists. Management: Monitor INR more closely. An anticoagulant dose increase may be needed after a barbiturate is initiated or given at an increased dose. Anticoagulant dose decreases may be needed following barbiturate discontinuation or dose reduction. Consider therapy modification
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification
Adverse Reactions
1% to 10%: Central nervous system: Drowsiness (1% to 3%)
<1%, postmarketing, and/or case reports: Abnormality in thinking, agitation, angioedema, anxiety, apnea, ataxia, bradycardia, central nervous system depression, sleep disorder (complex sleep-related behaviors, including cooking, driving, eating, and making phone calls while sleeping), confusion, constipation, dizziness, exfoliative dermatitis, fever, hallucination, headache, hepatotoxicity, hyperexcitability, hyperkinesis, hypotension, hypoventilation, insomnia, megaloblastic anemia, nausea, nervousness, nightmares, pain at injection site, skin rash, syncope, vomiting
Warnings/Precautions
Concerns related to adverse effects:
- CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
- Hypersensitivity reactions: Postmarketing studies have indicated that the use of hypnotic/sedative agents for sleep has been associated with hypersensitivity reactions including anaphylaxis as well as angioedema.
- Paradoxical responses: May cause paradoxical responses, including agitation and hyperactivity, particularly in acute pain, chronic pain and pediatric patients.
- Sleep-related activities: An increased risk for hazardous sleep-related activities such as sleep-driving; cooking and eating food, and making phone calls while asleep have also been noted. Discontinue treatment in patients who report a sleep-driving episode.
Disease-related concerns:
- Cardiovascular disease: Use with caution in patients with cardiovascular disease; may cause hypotension.
- Depression: Use with caution in patients with depression or suicidal tendencies.
- Drug abuse: Use with caution in patients with a history of drug abuse or acute alcoholism; potential for drug dependency exists. Tolerance, psychological and physical dependence may occur with prolonged use.
- Hepatic impairment: Use with caution in patients with hepatic impairment.
- Renal impairment: Use with caution in patients with renal impairment.
- Respiratory disease: Use with caution in patients with respiratory disease; may cause respiratory depression.
Concurrent drug therapy issues:
- Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.
Special populations:
- Pediatric: Use with caution in children.
Other warnings/precautions:
- Appropriate use: Symptomatic treatment of insomnia should be initiated only after careful evaluation of potential causes of sleep disturbance. Failure of sleep disturbance to resolve after 7-10 days may indicate psychiatric and/or medical illness.
- Withdrawal: Abrupt cessation may precipitate withdrawal, including status epilepticus in epileptic patients.
Monitoring Parameters
Blood pressure, heart rate, respiratory rate, CNS status; liver function, renal function
Pregnancy
Pregnancy Risk Factor
D
Pregnancy Considerations
Barbiturates can be detected in the placenta, fetal liver, and fetal brain. Fetal and maternal blood concentrations may be similar following parenteral administration. An increased incidence of fetal abnormalities may occur following maternal use. When used during the third trimester of pregnancy, withdrawal symptoms may occur in the neonate including seizures and hyperirritability; symptoms may be delayed up to 14 days. Use during labor does not impair uterine activity; however, respiratory depression may occur in the newborn; resuscitation equipment should be available, especially for premature infants.
Patient Education
- Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
- Patient may experience fatigue, dizziness, headache, loss of strength and energy, dry mouth, or nausea. Have patient report immediately to prescriber signs of depression (thoughts of suicide, anxiety, emotional instability, or illogical thinking), engaging in activities and not remembering, agitation, anxiety, behavioral changes, confusion, sensing things that seem real but are not, or trouble with memory (HCAHPS).
- Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.
