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Obese women may need higher medication dose during fertility therapy
Obese women who are undergoing assisted reproductive therapy may have different dosage requirements for the gonadotropin-releasing hormone antagonist cetrorelix to prevent premature ovulation, according to study results.
“Our findings indicate obese women may need a different or increased dosing regimen to improve fertility treatment outcomes,” Nanette Santoro, MD, of the University of Colorado at Denver, said in a press release. “Given the cost of [in vitro fertilization] and stress of infertility, it is important to maximize each woman’s chances of conceiving a child.”
Nanette Santoro
Researchers studied 10 normal-weight and 10 obese women with regular menses and normal baseline prolactin, thyroid-stimulating hormone and blood count. The two groups were similar in race and ethnicity; however, the mean age of obese participants was 32.5 years, whereas the mean age of normal-weight women was 27.3 years. Women were excluded from the study if they had chronic diseases or used medications that could affect reproductive hormones; were attempting pregnancy; exercised more than 4 hours each week; or used exogenous sex steroids in the last 3 months.
According to researchers, a single dose of cetrorelix (Cetrotide, EMD Serono) is expected to suppress luteinizing hormone for 96 hours. Cetrorelix was measured in serum samples after administration. Half of the obese women exhibited rebound of luteinizing hormone, defined as a 50% increase in luteinizing hormone, in a 14-hour post-dose period vs. none of the regular-weight women. The distributional half-life of cetrorelix was lower compared with the normal-weight group (8.1 vs. 12.7; P=.02). Analysis showed that age was not a significant covariant for dose half-life, clearance or volume of distribution, but significant correlations were shown between BMI, half-life and clearance.
“If the [gonadotropin-releasing hormone] antagonist clears from a woman’s body too quickly, there is a risk that the brain will signal the body to discharge the eggs from the ovaries too early,” Santoro said. “We were surprised to find obese women were more likely to experience this, and it may be one reason why overweight and obese women have a higher rate of unsuccessful [in vitro fertilization] cycles than normal-weight women do.”
Disclosure: The researchers report no relevant financial disclosures.
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