Prescription of isotretinoin by Australian dermatologists diverges from international guidelines in starting dose, dose increments and weaning practices.

An online survey of 118 respondents from 654 dermatologists found most (61.2%) initiated low-dose isotretinoin with 10 or 20 mg per day.

“This does not conform to the weight-based dosing regimen adopted in UK, USA and EU guidelines but is in line with the ACD which allows for daily dose be based on response and adverse effects,” the study said.

The survey, reported in Clinical and Experimental Dermatology, said most prescriptions (85.3%) had dose increases during treatment.

“Of these, 38.1% commenced with 10-20 mg per day and increased after 4 weeks as tolerated, without consideration to weight. Only 2.1% increased from 0.5mg/kg to 1mg/kg after 4 weeks in line in USA guidelines. Both UK and USA guidelines suggest treatment duration be guided by reaching a cumulative dose between 120-150mg/kg.”

The survey also found more than half of respondents (54.4%) determined treatment endpoint was being clear of active acne for 2 months.

“UK guidelines noted that the evidence for treatment endpoint based on sustained skin clearance is scarce, but included it in the guidelines based on clinical experience. It has been prioritised as a future research area,” the investigators said.

The survey said isotretinoin was weaned by 25.2% of respondents once treatment endpoint had been reached.

“After ceasing treatment, 26.6% recommended maintenance treatment with 61.3% using a topical retinoid and 12.9% cosmeceuticals.”

The survey found baseline and monitoring investigations were consistent with international guidelines.

The survey also revealed that 91% of dermatologists did not consider a prior or current history of depression a contraindication to treatment.

This was despite mood change being the most common adverse event leading to premature cessation of treatment and the fact that the ACD position statement recommends clinical assessment of the mental health of patients prior to isotretinoin prescription.

“The results suggest discordance between perception of isotretinoin causing mood change and the available evidence.”

“Further research is required to build the evidence base to support dosing, treatment duration and endpoint, and thresholds for ceasing due to mental health concerns,” the researchers said.

Commenting on the findings, Dr Jo-Ann See from Central Sydney Dermatology, said most dermatologists were well informed and prescribing was now a lot more individual.

Dr See, co-chair of All About Acne, said starting on a low dose and titrating according to response was appropriate.

She said weight-based dosing can have issues.

“I can have a 50 kg female and an 80 kg male and the response is individually variable so that the woman might be able to take more.”

She agreed that skin clearance should be the treatment endpoint noting that many patients could still have acne at the end of a six-month course.

“That more than a quarter of respondents offered maintenance treatment speaks to the fact that acne is a chronic disease, can last a long time and can be retriggered.”

Dr See added that most dermatologists would ask about a past history of depression but given the idiosyncratic nature of mood change as an adverse effect with isotretinoin, it might not necessarily stop them prescribing.

“It might be a flag to start low and slow,” she said.

She said it was disappointing that only 18% of dermatologists returned the survey.