The weight loss drug orlistat may prove to be a useful adjunct in the treatment of polycystic ovarian syndrome, according to findings from a small randomized study that compared the drug with metformin.
“[We've] demonstrated the therapeutic potential of orlistat in PCOS,” said Vijay Jayagopal, M.D., of the University of Hull (England) and his associates.
After a 12-week treatment period, 10 women treated with orlistat lost significantly more weight than 11 patients treated with metformin (a 4.7% vs. a 1% reduction) and had similar, statistically significant reductions in total serum testosterone (J. Clin. Endocrinol. Metab. 2005;90:729-33).
Neither drug produced significant reductions in fasting insulin, insulin resistance, sex hormone-binding globulin, or any of several lipid parameters studied.
In a written statement, Andrea E. Dunaif, M.D., president-elect of the Endocrine Society, said further research is needed to determine “where [weight-loss medications] will fit into the treatment of PCOS.”
The current study, however, “suggests that [the] medications may be an effective treatment option for not only the obesity but also the testosterone excess associated with PCOS,” said Dr. Dunaif of Northwestern University, Chicago.
Before drug treatment, all 21 patients—white women with PCOS—underwent an 8-week period of dietary modification (there were no significant changes in weight); they were then randomized to receive orlistat, which inhibits triglyceride and lipid absorption, or the insulin-sensitizing agent metformin.
Compared with baseline, a significant reduction in serum testosterone was observed after treatment in both the orlistat-treated group (approximately 94 ng/dL vs. 115 ng/dL) and the metformin-treated group (approximately 97 ng/dlL vs. 120 ng/dL).
Investigators noted that despite the lack of statistically significant improvements in many of the endocrine and metabolic parameters studied, the percentage changes from baseline were “more marked” in the orlistat group.
This may suggest that “the weight reduction had an overall stronger impact on these parameters than the insulin-sensitizing effect of metformin, the mechanism of which remains largely unknown,” they said.
Insulin resistance was calculated using the homeostasis model of assessment (HOMA-IR) method. The lack of statistically significant improvement in insulin resistance may be due in part to the large variability in HOMA-IR values in such a small group of patients, Dr. Jayagopal and his associates said.
The investigators did not collect information on menstrual change and ovulation, and the study was not powered to assess lipid changes. Such information is “clearly important” to acquire in larger studies, the investigators said.
In the meantime, Dr. Dunaif said, “we know that metformin is a proven and effective treatment for women with polycystic ovary syndrome.”