What this test measures
Urine immunoassay detects barbiturate class compounds (phenobarbital, butalbital, pentobarbital, secobarbital, amobarbital). Standard cutoff 200 ng/mL. Confirmation by GC-MS distinguishes specific compounds. Most modern medical use is phenobarbital for epilepsy (especially in Indian peripheral hospitals as a cheap, effective anticonvulsant) and butalbital in some combination headache medications.
Why it matters
Indian use scenarios: workplace / pre-employment drug screening, addiction-treatment monitoring, medico-legal evaluation in suspected suicide attempt / accidental overdose, athletic drug control (banned). Recreational barbiturate abuse is uncommon in India today (largely replaced by benzodiazepines). Therapeutic phenobarbital monitoring uses a separate quantitative serum test (10–40 µg/mL therapeutic range) rather than the urine screen.
How to prepare
Random urine sample, chain-of-custody if for legal / employment purposes. Disclose phenobarbital (Gardenal) for epilepsy, butalbital-containing analgesics, and any sedative-hypnotic use.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Urine Barbiturates (ng/mL)[1][2] | Negative (< 200 ng/mL screen cutoff) | Negative — no recent barbiturate use within the detection window. | Positive (≥ 200 ng/mL screen) — confirm with GC-MS. Likely sources: prescribed phenobarbital, butalbital-containing analgesics, rare recreational use, or barbiturate intoxication. Quantitative serum testing is needed for therapeutic monitoring. |
Barbiturate detection windows
| Substance | Detection window (urine) | Notes |
|---|---|---|
| Short-acting (pentobarbital, secobarbital) | 1–4 days | Recreational use |
| Intermediate (amobarbital, butalbital) | 2–7 days | Often in combination analgesics |
| Long-acting (phenobarbital) | 2–3 weeks | Epilepsy treatment |
Frequently asked questions
Will my epilepsy medication test positive?
Yes — phenobarbital (Gardenal) prescribed for seizures produces a positive urine barbiturate screen, often for 2–3 weeks after the last dose. Disclose your prescription.
Are barbiturates still commonly used?
Phenobarbital is still widely used in India for paediatric and neonatal seizures. Most other barbiturates have been replaced by benzodiazepines for sedation and propofol for anaesthesia.
How long after taking phenobarbital will I test positive?
Phenobarbital has a long half-life (~80 hours) so urine remains positive for 2–3 weeks after a single dose; longer with chronic therapy.
Can headache medication cause a positive?
Yes — butalbital is in some combination headache products (Fioricet) and can produce positive urine screens for several days.
What is the difference between this and therapeutic monitoring?
Urine screening is qualitative (positive / negative). Therapeutic phenobarbital monitoring uses a quantitative serum assay (target 10–40 µg/mL) to titrate dose against seizure control.
Related Drugs / Therapeutic Monitoring tests
Tests commonly ordered alongside BARBITURATES, or that help interpret an unexpected result.
Sources & references
- SAMHSA — Urine Drug Testing Guidelines · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Drug Testing · accessed 2026-05-30T00:00:00.000Z
- StatPearls — Barbiturate Toxicity · accessed 2026-05-30T00:00:00.000Z
Book with Zelnoo
Get your BARBITURATES test done at home — transparent prices, NABL-accredited labs.
Zelnoo lets you compare diagnostic test prices across NABL-accredited labs in Mumbai & Thane, book a free home phlebotomist visit, and receive digital reports in 24–48 hours into a consent-first report vault. No subscriptions, no membership fees — pay only for the test you book.
Book BARBITURATES now