Exploring melatonin prescribing among customers of compounding pharmacies in Australia

To the Editor: In Australia, when melatonin is requested in doses higher than those available in preprepared formulations, in different dosage forms, or for people under 55 years of age, private prescriptions and extempora-neous preparations are often used. There is evidence of efficacy of melatonin in shiftwork-related sleep disorders, jet lag, circadian rhythm disorders, and for older people with chronic insomnia, but not for insomnia generally.1-3 There is concern over increasing use of melatonin in children, but no current data exist for actual melatonin usage patterns in Australia. In September 2010, we conducted a 2-week prospective drug use audit of melatonin prescriptions dispensed to patients by Australian compounding pharmacies.

All pharmacies of the Professional Compounding Chemists of Australia (PCCA) (n = 153) received audit forms and explanatory information sheets, followed up by two telephone calls. The audit form requested patient details, the melatonin prescription, prescriber, dose amount and formulation prescribed, directions on prescription, and purpose of medication. This study was approved by the Human Research Ethics Committee of the University of Sydney.

Forty-one pharmacies completed 228 audits, a response rate similar to recent pharmacy-based surveys.4 Also, 42 pharmacies estimated melatonin prescriptions in the audit period without completing patient details.

The demographic details of respondents (Box) were similar to those in a previous survey of Australian compounding pharmacies.5 A total of 1463 melatonin prescriptions were reported as dispensed in the 2 weeks by 83 pharmacies (17.63 per pharmacy). In the detailed audit, the median age of people for whom melatonin was prescribed was 12 years; 56.4% (128/227) were male; the average dose prescribed was 4.3 mg ± 2.5 mg (range, 0.5 mg–20 mg); the most common reason for prescribing melatonin was to help sleep in cases of attention deficit hyperactivity disorder (ADHD); and paediatricians were the most common prescriber (43.0%; 96/223). Analysis of the non-responders showed that responders were not different to non-responders in age, sex, years of experience or pharmacy prescription volume. Extrapolating the results, 70 132 prescriptions (17.63 × 26 × 153) are estimated to be compounded in the 153 compounding pharmacies annually. This staggering figure does not include non-PCCA pharmacies, compounding hospital pharmacies, melatonin purchases without prescription (generally via the internet), or Circadin (Neurim Pharmaceuticals) prescriptions. Circadin was not included in our study as it was introduced in mid 2010 and there had been only a few sales by September 2010, and it is approved only for people over 55 years of age with primary insomnia.

In conclusion, we found that melatonin was frequently dispensed, with many cases of off-label use, to both adults and children, particularly for insomnia in children with ADHD and autism. Melatonin has limited long-term safety data, and the long-term effect on gonadal development, particularly with high doses, is unclear. The efficacy and safety of melatonin in children will only be established through well designed trials of high methodological quality and sufficient sample size.