Effect of Weight and/or Obesity on Caspofungin Drug Concentrations

Inclusion Criteria: * Male and female subjects, age 18 years of age or older, of all racial and ethnic origins. English and/or Spanish speaking volunteers are eligible to participate. Exclusion Criteria: * Pregnant or nursing or unwilling to use a reliable contraception method during the study. The effects of caspofungin on pregnancy are unknown. In addition, the metabolic changes that accompany pregnancy may alter the concentration-time profile of caspofungin, so that the pregnancy and post-partum state would be a confounding variable. * Abnormal liver function tests: transaminases\>10 times upper limit of normal, Alkaline phosphatase\>5 times upper limit of normal, total bilirubin\>5 times upper limit of normal. * History of allergies to echinocandins. * Echinocandins are contraindicated for any reason. * Volunteers unwilling to comply with study procedures. * Suspected or documented systemic fungal infection. * Concomitant use of rifamycins, tacrolimus, or cyclosporine