ZALEPLON
Clinical safety rating: safe
Animal studies have demonstrated safety
Selective agonist of the benzodiazepine site on GABA-A receptors, enhancing GABA-mediated chloride conductance and neuronal inhibition. Binds preferentially to the α1 subunit-containing receptors.
| Metabolism | Primarily hepatic via aldehyde oxidase (major pathway) and CYP3A4 (minor pathway); undergoes first-pass metabolism. Active metabolite: 5-oxo-zaleplon (inactive). |
| Excretion | Approximately 70% of a dose is excreted as metabolites in urine (primarily as 5-oxo-zaleplon and other oxidative metabolites) and about 30% in feces. Less than 1% is excreted unchanged in urine. |
| Half-life | The terminal elimination half-life is approximately 1 hour (range 0.9–1.1 hours) in healthy adults. This short half-life minimizes next-day residual effects and is consistent with its use for sleep induction without significant morning sedation. |
| Protein binding | Plasma protein binding is approximately 60% (primarily to albumin). |
| Volume of Distribution | Volume of distribution is approximately 1.4 L/kg (range 1.0–1.8 L/kg) in adults, indicating extensive distribution into tissues. |
| Bioavailability | Oral bioavailability is approximately 30% due to extensive first-pass metabolism. Bioavailability is not significantly affected by food, but a high-fat meal may delay absorption and reduce peak concentrations. |
| Onset of Action | Oral: Onset of action occurs within 15–30 minutes following oral administration, with peak plasma concentrations at approximately 1 hour. |
| Duration of Action | Duration of action is approximately 3–4 hours based on clinical efficacy in sleep latency reduction. The short half-life limits duration, making it suitable for sleep initiation rather than maintenance. |
| Molecular Weight | 305.36 |
10 mg orally once daily at bedtime; range 5-20 mg.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment; not recommended in severe renal impairment (CrCl <30 mL/min) due to insufficient data. |
| Liver impairment | Child-Pugh A: 5 mg at bedtime; Child-Pugh B: 5 mg at bedtime (use with caution); Child-Pugh C: contraindicated. |
| Pediatric use | Not approved for pediatric use; safety and efficacy not established in patients <18 years. |
| Geriatric use | Initial dose 5 mg at bedtime; may increase to 10 mg if needed and tolerated; increased risk of falls and cognitive impairment. |
| 1st trimester | Avoid: insufficient data; potential fetal harm in animal studies. |
| 2nd trimester | Avoid: limited human data; risk of adverse effects on fetal development. |
| 3rd trimester | Avoid: neonatal respiratory depression and withdrawal symptoms may occur. |
Clinical note
CNS depressants including alcohol increase sedation risk Can cause complex sleep behaviors like sleep-driving.
| Placental transfer | Zaleplon crosses the placenta (no specific percentage available; based on class, likely moderate transfer). |
| Breastfeeding | Zaleplon is excreted into breast milk in low amounts; however, due to potential adverse effects on the infant (e.g., sedation), use only if clearly needed and monitor infant for drowsiness. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Common Effects | Dizziness |
| Serious Effects |
Hypersensitivity to zaleplon or any componentSevere hepatic impairmentConcurrent use with alcohol or other CNS depressants (relative, but absolute in practice)
| Precautions | Risk of CNS depression and daytime sedation, Complex sleep behaviors (e.g., sleep-driving, preparing/eating food, making phone calls) while not fully awake, Worsening of depression or suicidal ideation, Anaphylaxis and angioedema (rare), Tolerance, dependence, and withdrawal symptoms with prolonged use, Respiratory depression in patients with compromised respiratory function, Use with caution in elderly due to increased risk of falls and cognitive impairment, Not recommended for long-term use (beyond 7-10 days) |
| Food/Dietary |
Loading safety data…
| L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. First trimester: Limited human data; animal studies show increased fetal loss and skeletal variations at high doses. Second/third trimester: Risk of neonatal respiratory depression, hypotonia, and withdrawal if used near term. Avoid use, especially during first and third trimesters. |
| Fetal Monitoring | Monitor maternal sedation, respiratory rate, and vital signs. Assess fetal heart rate and uterine activity if used during labor. Evaluate neonatal respiratory function, tone, and alertness at birth if used near delivery. |
| Fertility Effects | No specific human data on fertility impairment. Animal studies show no significant effects on fertility at therapeutic doses. |
| High-fat meals delay absorption and reduce peak plasma concentration of zaleplon, potentially diminishing its hypnotic effect. Avoid taking with or immediately after a heavy, high-fat meal. No other specific food interactions noted. |
| Clinical Pearls | Zolpidem is a non-benzodiazepine hypnotic, not zaleplon. For zaleplon: short half-life (1 hr), minimal next-day sedation; ideal for sleep-onset insomnia. Avoid in patients with severe hepatic impairment. Can be taken at bedtime or after waking up in middle of night if >4 hrs left before awakening. Not recommended for chronic use >7-10 days. |
| Patient Advice | Take immediately before bedtime or after waking up in the middle of the night if at least 4 hours remain before planned awakening. · Do not take with alcohol or other CNS depressants. · Do not exceed one dose per night. · May cause dizziness, drowsiness, or impaired coordination; avoid driving or hazardous activities after taking. · Risk of complex sleep behaviors (sleep-driving, preparing/eating food, making phone calls) with amnesia; discontinue if occurs. · Use lowest effective dose for shortest duration (typically 7-10 days). · Abrupt discontinuation may cause withdrawal symptoms; taper if used long-term. · Not recommended for use beyond 7-10 days due to lack of efficacy data. · Avoid taking with or immediately after a high-fat meal (delays absorption and reduces effect). |