Exposure to methylphenidate during peri-adolescence affects endocrine functioning and sexual behavior in female Long-Evans rats.

The present study was designed to test the effects of methylphenidate (MPH) exposure on the maturation of endocrine functioning and sexual behavior. Female rat pups received either MPH (2.0mg/kg, i.p.) or saline twice daily between postnatal days 20-35. This period of exposure represents the time just prior to puberty as well as puberty onset. Approximately five weeks after the last injection of MPH or saline, female subjects were hormone-primed and tested during their first sexual experience. Subjects were given the choice to interact with a sexually active male or a sexually receptive female rat (i.e., the partner-preference test). The partner-preference paradigm allows us to assess multiple aspects of female sexual behavior. MPH exposure during peri-adolescence delayed puberty and, when mated for the first time, affected sexual behavior (e.g., increased time spent with the male stimulus and decreased the likelihood of leaving after mounts) during the test of partner preference. When monitoring estrous cyclicity, female subjects treated with MPH during peri-adolescence frequently experienced irregular estrous cycles. The results of the present study suggest that chronic exposure to a therapeutic dose of MPH around the onset of puberty alters long-term endocrine functioning, but with hormone priming, increases sensitivity to sexual stimuli.

Treatment of thrombosis with fondaparinux (Arixtra) in a patient with end-stage renal disease receiving hemodialysis therapy.

Treatment of thrombosis in children with end-stage renal disease (ESRD) is extremely challenging owing to the underlying risk of bleeding. Fondaparinux (Arixtra, Sanofi-Synthélabo), a synthetic pentasaccharide, is contraindicated in patients with compromised renal function as it is excreted via kidneys. We describe a unique case with ESRD and pulmonary embolism who was treated with fondaparinux owing to the toxicity and poor compliance with low-molecular-weight heparin. Despite regular hemodialysis, a gradual rise in drug levels was observed without significant bleeding complications. This report implies that although low dose fondaparinux can be an option in patients with ESRD under special circumstances, guidelines for laboratory monitoring and appropriate dose adjustments are urgently required to ensure the safety of the patient.