The current study is part of a large multi-investigator grant to look at the pharmacogenetics of a number of membrane transporters. Previously, we have recruited a cohort of healthy volunteers (Studies of Pharmacogenetics in Ethnically-diverse Populations, or SOPHIE) and have resequenced the coding region of a number of membrane transporter genes to identify genetic polymorphisms in these genes. We plan to take a genotype-to-phenotype approach to study the influence of specific polymorphisms in the intestinal transporters, such as the novel organic cation transporters 1 and 2 (OCTN1 and OCTN2) genes on the bioavailability of gabapentin in healthy subjects. Eligible subjects will have a single inpatient study visit, during which they will take a single dose of gabapentin, and provide blood and urine samples over the course of 36 hours (5 terminal elimination gabapentin half-lives) for pharmacokinetic analysis.

Detailed description pending

Inclusion Criteria:

• Subjects must have previously participated in the "SOPHIE" study.
• Subjects will be between the ages of 18 and 40 years old
• Subjects will have been selected as healthy by medical history questionnaire and screening blood work (CBC, Comprehensive Metabolic panel).
• Subjects will be taking no regular medications and will have normal renal function.

Exclusion Criteria:

• Pregnant
• Have a new history indicating they are no longer healthy; Individuals with anemia (hemoglobin < 12 g/dL), an elevation in liver enzymes to higher than double the respective normal value, or elevated creatinine concentrations (males ≥ 1.5 mg/dL, females ≥ 1.4 mg/dL), will be excluded.
• Taking a medication that could confound study results
• Do not consent to participate in the study.