Oxybutynin for methadone-induced sweating in pregnancy
Dear Sir,
Methadone substitution therapy in pregnancy provides favourable out- comes for mother and infant com- pared to illicit drug use.1 Continuation during pregnancy is vital; opioid withdrawal can result in miscarriage or premature delivery. Problematic perspiration occurs in up to 78% of patients receiving methadone,2 which can be intolerable, resulting in dis- continuation.
A 29-year-old woman taking 75 mg of methadone daily was 23 weeks pregnant. She reported several weeks of severe sweating. This was contin- uous and affected her head, back, axilla and groin. It worsened with exercise and at night. She described feeling like she was ‘always getting out of the shower’ and changed clothes several times a day. When attending clinic, she required towels to wipe sweat from her head and arms. A recent dose increase of methadone had successfully man- aged her craving and there were no other symptoms of opioid with- drawal. Worryingly, due to sweating, she considered reducing her metha- done against advice.
The patient was prescribed venlafax- ine, which can cause sweating. Discontinuation of this was dis- missed, as her depression was well controlled and there were concerns about venlafaxine withdrawal symp-

methadone treatment, we explored medication options for hyperhidrosis.
Oxybutynin is an anticholinergic indicated for urinary dysfunction. A placebo-controlled study in general- ised hyperhidrosis3 demonstrated improvement of symptoms and quality of life. The single case report of oxybutynin for sweating associ- ated with methadone was success- ful.4 There have been no reports in pregnant patients on methadone.
Oxybutynin is classified as Category B, indicating no definitive data dem- onstrating safety; however, the pre- dicted impact of exposure was low. The patient gave written informed consent for the use in pregnancy, off-label indication and publication of this case.
Oxybutynin commenced at 5 mg twice daily. Following the initial dose, she experienced reduction in sweating, and after 7 days, was no longer bothered by sweating. She did not note any side effects, other than a brief delay in passing urine. Following delivery of the baby, oxy- butynin was discontinued.
This case supports a role for oxybu- tynin for methadone-induced hyper- hidrosis. It has been efficacious and well tolerated by a pregnant woman. Further observations will determine whether oxybutynin should become a treatment option for this disabling condition. While it was well toler- ated in this case, anticholinergic effects (dry mouth, confusion, gas- trointestinal dysfunction, etc.)

pregnancy. Discontinuation at birth should occur as anticholinergics can interfere with breastfeeding.

The author reports no conflict of interest. The author alone is responsible for the content and writing of the paper.

The author received no financial support for publication of this case.

James Anthony (Tony) Harley https://orcid.org/0000-

⦁ World Health Organization. Guidelines for the identi- fication and management of substance use and sub- stance use disorders in pregnancy. https://apps.who. int/iris/handle/10665/107130
⦁ Haber PS, Elsayed M, Espinoza D, et al. Consti- pation and other common symptoms reported by women and men in methadone and buprenorphine maintenance treatment. Drug Alcohol Depend 2017; 181: 132–139.
⦁ Schollhammer M, Brenaut E, Menard-Andivot N, et al. Oxybutynin as a treatment for generalized hyperhidro- sis: a randomized, placebo-controlled trial. Br J Derma- tol 2015; 173: 1163–1168.
⦁ Hong J, Lee J, Totouom-Tangho H, et al. Methadone- induced hyperhidrosis treated with oxybutynin. J Addict Med 2017; 11: 237–238.

James Anthony (Tony) Harley Community Alcohol and Drug Service and Christchurch Opioid Recovery Service, Canterbury District Health Board, Hillmorton Hospital, Christchurch, NZ.
DOI: 10.1177/1039856220965055

toms. To preserve engagement with should be monitored throughout


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