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oxazepam (Serax)
Tradename: Serax. DEA-controlled substance: class 4.
Indications:
1) treatment of anxiety
2) short-term management of panic attacks
3) muscle spasms
4) alcohol withdrawal
5) anticonvulsant in management of simple partial seizures
Contraindications:
1) pre-existing CNS depression
2) narrow-angle glaucoma
Dosage: (1 mg lorazepam = 15 mg oxazepam)
1) 10-15 mg PO TID/QID [1]
2) 30-120 mg/24 hours PO TID/QID [2]
3) 15-30 mg PO every 6-8 hours (alcohol withdrawal)
Tabs: 10, 15, 30 mg.
Pharmacokinetics:
1) well absorbed orally
2) onset of action is 10-30 minutes
3) peak effect in 2-4 hours
4) 1/2life is 5-20 hours
5) duration of action is 6-8 hours
6) metabolized by conjugation in the liver [6]
- metabolites are pharmacologically inactive [2]
7) metabolites eliminated in the urine
Adverse effects:
1) common (> 10%)
- drowsiness, fatigue, impaired coordination, lightheadedness, memory impairment, insomnia, dysarthria, anxiety, decreased libido, depression, headache, dry mouth, constipation, diarrhea, decreased salivation, nausea, vomiting, tachycardia, chest pain, blurred vision, sweating, rash, increased or decreased appetite
2) less common (1-10%)
- confusion, nervousness, syncope, dizziness, akathesia, increased salivation, hypertension, rigidity, tremor, dermatitis, nasal congestion, weight gain or weight loss, hyperventilation, tinnitus, muscle cramps
3) uncommon (< 1%)
- menstrual irregularities, blood dyscrasia, reflex slowing urinary incontinence
4) other [3]
- agitation
- anterograde amnesia
- hallucinations
- addiction
- hiccups
- myocardial depression, respiratory depression
- relaxation of the lower esophageal sphincter (GERD)
Drug interactions:
1) agents that decrease metabolism &/or increase absorption of oxazepam
a) disulfiram
b) nefazodone
c) fluoxetine
d) fluvoxamine
e) cimetidine
f) grapefruit juice
2) CNS depressants in combination increase CNS depression
3) antiepileptic agents & rifampin increase metabolism of benzodiazepines
4) flumazenil (Romazicon) antagonizes effects of benzodiazepines
Laboratory:
1) specimen: serum, plasma (EDTA) urine
2) methods:
a) serum/plasma: GLC, HPLC, GC-MS
b) urine: EIA, FPIA
3) interferences: carbamazepine may interfere with GLC
4) labs with Loincs
- oxazepam in specimen
- oxazepam in hair
- oxazepam in tissue
- oxazepam in body fluid
- oxazepam in blood
- oxazepam in gastric fluid
- oxazepam in meconium
- oxazepam in saliva
- oxazepam in serum/plasma
- oxazepam in urine
- oxazepam in vitreous fluid
Mechanism of action:
- potentiates GABA's inhibitory effects by increasing neuronal membrane permeability to chloride
Interactions
drug interactions
drug adverse effects (more general classes)
General
benzodiazepine
Properties
MISC-INFO: elimination route KIDNEY
1/2life 5-15 HOURS
therapeutic-range 0.2-1.4 UG/ML
protein-binding 96-98%
elimination by hemodialysis -
pregnancy-category D
safety in lactation -
Database Correlations
PUBCHEM cid=4616
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996.
- Manual of Medical Therapeutics, 28th ed, Ewald &
McKenzie (eds), Little, Brown & Co, Boston, 1995,
pg 7
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998 - not on National VA formulary
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed.,
W.B. Saunders, 1995
- UCLA Intensive Course in Geriatric Medicine & Board Review,
Marina Del Ray, CA, Sept 12-15, 2001