Low-dose phenobarbitone as an indicator of compliance with drug therapy.
1 To assess the potential value of low-dose phenobarbitone (PB) as a marker of compliance we studied the relationship between plasma level of PB and dose (2-16 mg daily) following 3 or 4 weeks treatment in healthy volunteers (n = 26) and in-patient volunteers (n = 7). 2 Also, to simulate poor compliance, PB levels were measured in some volunteers following alternate-day (n = 6) or short-term (n = 5) treatment with similar doses. These levels, expressed as the level: dose ratios (LDRs), did not overlap with those obtained following 3 or 4 weeks of daily PB intake. 3 To evaluate the efficacy of this marker in patients taking other drugs we gave a group of out-patients (n = 24) compound tablets containing B vitamins and a small dose (16 mg) of PB; their compliance over 2-5 weeks was assessed both by measuring plasma levels of PB and residual tablet counting. 4 In the latter study, as well as providing absolute evidence of good compliance by many patients, the plasma levels of PB proved particularly valuable when non-compliant individuals 'forgot' to bring their residual tablets. 5 We suggest that phenobarbitone, in doses low enough to be non-sedative and non-enzyme inducing, is potentially useful as a pharmacological indicator of compliance with drug therapy.
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D010634:Phenobarbital / Q000097:blood; D014635:Valproic Acid / Q000008:administration & dosage; D014859:Warfarin / Q000008:administration & dosage
D000959:Antihypertensive Agents; D014859:Warfarin; D014635:Valproic Acid; D010634:Phenobarbital