Myo-inositol in the treatment of premenstrual dysphoric disorder.

Objective: Premenstrual dysphoric disorder (PMDD) is a mood disorder disrupting social and/or occupational life of affected women. Premenstrual dysphoric disorder etiology is unknown, although a pivotal role is played by the serotoninergic system. Indeed, one of the most effective treatments is selective serotonin reuptake inhibitors. Several studies have proposed a selective serotonin reuptake inhibitor-like role for myo-inositol, likely due to the fact that myo-inositol is the second messenger of serotonin. In the present study, we aimed to investigate the effect of myo-inositol in the treatment of PMDD.

Methods: We used a two-phase clinical trial approach (phase I: placebo washout; phase II: comparisons between treatment and placebo) and treated PMMD patients with two different myo-inositol formulations: powder or soft gel capsules. We decided to test these two formulations because according to the manufacturer, 0.6 g of myo-inositol in soft gel capsule has a pharmacokinetic equivalent to 2 g of myo-inositol in powder.

Results: Our results showed a significant improvement of three different scales: a reduction in the Daily Symptoms Records scale and an improvement of the Hamilton Depression Rating and Clinical Global Impression-Severity of Illness scales. Results were similar for both formulations.

Conclusions: In the present study, by using a new pharmaceutical formulation, we were able to clearly prove the efficacy of myo-inositol in PMDD.