A randomized controlled trial of intranasal oxytocin in Phelan-McDermid syndrome.

Only 18 children were randomized, and 16 were included in the efficacy analysis, so the study was too small to rule out modest effects. The trial stopped after three years due to recruitment challenges, which may have left it underpowered for small effects. The oxytocin and placebo groups had different baseline social withdrawal scores (mean 20.1 in placebo and 14 in oxytocin). The main outcome and most other outcomes relied on subjective parent report and had not been rigorously validated for PMS. The open-label extension had no control group, so changes between week 12 and week 24 cannot be compared with placebo. Five participants were also receiving stable psychotropic medications: aripiprazole, tizanidine, mirtazapine, doxepin, clonidine, lisdexamfetamine, divalproex sodium, melatonin, gabapentin, oxcarbazepine, and levetiracetam. The dosing did not account for the broad age range, pubertal status, or baseline oxytocin levels, and six insufflations twice daily may have been difficult to administer at home. Compliance was monitored by parent report and drug diaries, so missed doses cannot be ruled out. Although all participants had SHANK3 haploinsufficiency, 12 had deletions and 6 had sequence variants, and the study was too small to examine these subsets.

The supplied text names the Beatrice and Samuel A. Seaver Foundation as the funder. No author conflict-of-interest statement is supplied.

Do not read the primary p value of 0.055 as evidence that oxytocin probably works. The study did not find a statistically significant difference from placebo, and the result remained non-significant after controlling for baseline social withdrawal scores (p = 0.088).