Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
SYMPAZAN vs DIASTAT
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
SYMPAZAN (clobazam) is a benzodiazepine that potentiates GABAergic inhibition via binding to the GABA-A receptor at the benzodiazepine site, enhancing chloride ion influx and neuronal hyperpolarization.
Diazepam enhances the effect of gamma-aminobutyric acid (GABA) at GABA-A receptors, increasing chloride ion conductance and neuronal hyperpolarization, leading to anxiolytic, sedative, muscle relaxant, and anticonvulsant effects.
FDA-approved for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients aged 2 years and older,Off-label: adjunctive therapy for other epileptic syndromes, anxiety disorders, and acute repetitive seizures
Status epilepticus (FDA-approved for acute management),Breakthrough seizures in patients on stable antiepileptic regimen (FDA-approved),Preoperative anxiety (off-label),Alcohol withdrawal syndrome (off-label),Muscle spasm (off-label)
10-20 mg orally three times daily (maximum 60 mg/day). If switching from another benzodiazepine, use equivalent dose.
Adult: 0.2 mg/kg (max 20 mg) rectally as a single dose; may repeat once after 4-12 hours if needed. Maximum cumulative dose: 40 mg per 24-hour period.
Terminal elimination half-life is approximately 20-30 minutes sublingually, prolonged to 2-3 hours in hepatic impairment. Clinical context: Short t½ necessitates repeated dosing for seizure clusters.
30–60 hours for diazepam; nordazepam (active metabolite) 50–120 hours. Prolonged in elderly, liver disease, and neonates
Primarily metabolized by CYP3A4 and CYP2C19 to N-desmethylclobazam, an active metabolite. N-desmethylclobazam is further metabolized by CYP2C19.
Primarily hepatic via CYP2C19 and CYP3A4; active metabolite desmethyldiazepam (with long half-life); minor pathways include glucuronidation.
Primarily renal excretion of unchanged drug (approximately 60-70%), with minor fecal elimination (10-15%) and metabolism.
Renal (primarily as glucuronide and sulfate conjugates; <5% unchanged), biliary/fecal minimal
Approximately 90-95% bound to albumin and alpha-1-acid glycoprotein.
98–99%; primarily albumin
Vd is 1-2 L/kg, indicating extensive tissue distribution beyond plasma volume.
0.8–1.0 L/kg; increased in obesity (1.5–2.5 L/kg), redistribution to adipose tissue prolongs half-life
Sublingual and buccal: 100% bioequivalent to intravenous; intranasal: approximately 80%.
Rectal: 90% (relative to IV, complete absorption). Oral: 100%
No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (Cr Cl <30 m L/min), use with caution and consider dose reduction; specific guidelines not established.
No specific dose adjustment required for renal impairment; however, use with caution in severe impairment (Cr Cl <10 m L/min) due to prolonged half-life.
Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate impairment (Child-Pugh A or B), reduce dose by 50% or administer with caution, as clobazam is extensively metabolized in the liver.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 50%. Child-Pugh Class C: Reduce dose by 75% or avoid use.
Based on body weight: 5 mg orally once daily for <30 kg, increase to 10 mg daily after 2 weeks if needed (max 20 mg/day). For ≥30 kg, 5-10 mg once daily initially, titrate to 20 mg/day (max 40 mg/day).
Children 2-5 years: 0.5 mg/kg (max 20 mg) rectally. Children 6-11 years: 0.3 mg/kg (max 20 mg) rectally. Children 12+ years: same as adult dosing. May repeat once after 4-12 hours if needed. Maximum cumulative dose: 40 mg per 24-hour period.
Initiate at 5 mg once daily, titrate slowly due to increased sensitivity to benzodiazepines and risk of falls. Maximum dose generally not to exceed 20 mg/day.
Initiate at lower end of dosing range (e.g., 0.1-0.15 mg/kg, max 10 mg) due to increased sensitivity and risk of falls; monitor for prolonged sedation and respiratory depression.
Concomitant use of benzodiazepines with opioids may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients for whom alternative treatment options are inadequate.
Concomitant use of benzodiazepines and opioids may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients for whom alternative treatment options are inadequate; limit dosages and durations to the minimum required; and follow patients for signs and symptoms of respiratory depression and sedation.
Respiratory depression,Sedation and somnolence,Risk of abuse, misuse, and addiction,Dependence and withdrawal reactions,Suicidal thoughts or behavior
Risk of respiratory depression, especially with concomitant CNS depressants; tolerance and physical dependence may develop; withdrawal symptoms including seizures after abrupt discontinuation; caution in elderly, debilitated patients, and those with hepatic impairment; may cause drowsiness or dizziness; not recommended for use in pregnancy (neonatal withdrawal).
Hypersensitivity to clobazam or any component of the formulation,Severe hepatic impairment (Child-Pugh Class C)
Known hypersensitivity to diazepam or any benzodiazepine; myasthenia gravis; severe respiratory insufficiency; severe hepatic insufficiency; sleep apnea syndrome; narrow-angle glaucoma (in patients receiving anticholinergic therapy).
Avoid grapefruit and grapefruit juice as they may increase levels of clobazam and its active metabolite. No other significant food interactions known.
No specific food interactions. Avoid grapefruit juice as it may increase diazepam levels. Alcohol can potentiate CNS depression.
Benzodiazepines are generally associated with increased risk of oral clefts when used in the first trimester. Use in the third trimester may cause neonatal sedation, withdrawal, or floppy infant syndrome. Specific fetal risk data for clobazam (Sympazan) are limited.
DIASTAT (diazepam) is classified as Pregnancy Category D. First trimester: Increased risk of congenital malformations, particularly cleft lip and palate, when used during the first trimester. Second and third trimesters: Chronic use may lead to fetal dependence and withdrawal symptoms postnatally; risk of floppy infant syndrome (hypotonia, lethargy, sucking difficulties) when administered near term.
Clobazam is excreted in breast milk. The milk-to-plasma ratio is approximately 0.3 to 0.5. Monitor infant for sedation, poor feeding, and weight gain. Avoid breastfeeding if possible.
Diazepam is excreted into breast milk with an M/P ratio of approximately 0.2-0.5. The American Academy of Pediatrics recommends use with caution due to potential accumulation and sedation in the infant. Avoid chronic use; if necessary, monitor infant for sedation, poor feeding, and weight gain.
Increased clearance of clobazam in pregnancy may require dose adjustments; monitor therapeutic response and adjust accordingly.
Due to increased volume of distribution and altered protein binding in pregnancy, total clearance of diazepam may be increased, potentially requiring higher doses to achieve therapeutic effect. However, routine dose adjustment is not recommended without clinical monitoring. Use lowest effective dose for shortest duration. Caution in third trimester due to increased risk of neonatal effects.
Clobazam oral film (SYMPAZAN) is a benzodiazepine approved for adjunctive treatment of seizures associated with Lennox-Gastaut syndrome in patients aged 2 years and older. It is available as a rapidly dissolving film that can be placed on the tongue. The active metabolite N-desmethylclobazam is primarily renally excreted; adjust dose in renal impairment. Avoid abrupt discontinuation due to risk of withdrawal seizures. CYP2C19 poor metabolizers have significantly higher exposure to the active metabolite; consider dose reduction. Can cause sedation, dizziness, and somnolence; monitor for respiratory depression especially with other CNS depressants. Abuse potential exists; use with caution in patients with history of substance abuse.
DIASTAT (diazepam rectal gel) is a formulation for acute management of seizure clusters. Administer rectally; monitor for respiratory depression, especially with concomitant CNS depressants. Do not exceed 5 doses per month or use for more than 5 episodes per month due to tolerance risk. Have flumazenil available for reversal.
Place the film on your tongue where it will dissolve quickly; do not chew or swallow it whole.,Take this medication exactly as prescribed; do not increase the dose or stop suddenly without talking to your doctor to avoid withdrawal seizures.,Avoid driving or operating heavy machinery until you know how this drug affects you, as it may cause drowsiness, dizziness, or blurred vision.,Avoid alcohol and other sedating medications while taking SYMPAZAN, as they can increase the risk of severe drowsiness and breathing problems.,Tell your doctor if you have kidney or liver disease, or if you have a history of substance abuse or depression.,If you miss a dose, take it as soon as you remember; if it is close to the next dose, skip the missed dose and continue your regular schedule. Do not double the dose.,Store the film at room temperature away from moisture and heat; keep each film in its sealed pouch until ready to use.
Use only as directed for episodes of increased seizure activity.,Administer rectally; do not reuse diapers/suppositories.,Monitor for drowsiness, dizziness, or breathing problems.,Avoid alcohol and other CNS depressants.,Store at room temperature; protect from light.,Seek emergency care if seizures last longer than usual or breathing is difficult.
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 SYMPAZAN vs DIASTAT, answered by our medical review team.
SYMPAZAN is a Benzodiazepine Anticonvulsant that works by SYMPAZAN (clobazam) is a benzodiazepine that potentiates GABAergic inhibition via binding to the GABA-A receptor at the benzodiazepine site, enhancing chloride ion influx and neuronal hyperpolarization.. DIASTAT is a Benzodiazepine Anticonvulsant that works by Diazepam enhances the effect of gamma-aminobutyric acid (GABA) at GABA-A receptors, increasing chloride ion conductance and neuronal hyperpolarization, leading to anxiolytic, sedative, muscle relaxant, and anticonvulsant effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between SYMPAZAN and DIASTAT depend on the specific clinical indication. These are both Benzodiazepine Anticonvulsant agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of SYMPAZAN is: 10-20 mg orally three times daily (maximum 60 mg/day). If switching from another benzodiazepine, use equivalent dose.. The standard adult dose of DIASTAT is: Adult: 0.2 mg/kg (max 20 mg) rectally as a single dose; may repeat once after 4-12 hours if needed. Maximum cumulative dose: 40 mg per 24-hour period.. 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 SYMPAZAN and DIASTAT 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. SYMPAZAN is classified as Category C. Benzodiazepines are generally associated with increased risk of oral clefts when used in the first trimester. Use in the third trimester may cause neonatal sedation, withdrawal, or. DIASTAT is classified as Category C. DIASTAT (diazepam) is classified as Pregnancy Category D. First trimester: Increased risk of congenital malformations, particularly cleft lip and palate, when used during the first. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.