The purpose of this study is to compare the bioequivalence of a test formulation of primidone tablets to an equivalent oral dose of the commercially available Mysoline®(primidone tablets) in adult subjects under fasting conditions.

The purpose of this study is to compare the bioequivalence of a test formulation of primidone tablets to an equivalent oral dose of the commercially available Mysoline® (primidone tablets) in adult subjects under fasting conditions.

Twenty-two healthy, non-smoking, non-obese male and female volunteers at least 18 years of age will be randomly assigned in a crossover fashion to receive each of two primidone dosing regimens in sequence with a 14 day washout period between dosing periods. On the morning of Day 1, after an overnight fast of at least 10 hours, subjects will receive either a single oral dose of the test formulation, primidone (1 x 50 mg tablet) or a single oral dose of the reference formulation, Mysoline® (1 x 50 mg tablet). After a 14 day washout period, on the morning of Day 15 after an overnight fast, subjects will receive the alternate regimen. Blood samples will be drawn from all participants before dosing and for 72 hours post dose at times sufficient to adequately define the pharmacokinetics of primidone. A further goal of this study is to evaluate the safety and tolerability of this regimen in healthy volunteers. Subjects will be monitored throughout the confinement portion of the study for adverse reactions to the study drugs and/or procedures. Blood pressure and heart rate will be obtained prior to dosing and at 3, 4, 6, 24 and 72 hours post-dose. All adverse events whether elicited by query, spontaneously reported or observed by clinic staff will be evaluated by the investigator and reported in the subject's case report form.

Inclusion Criteria:

• male or female
• at least 18 years of age
• weight must be 15% of ideal weight for height and frame
• subjects must be in good health and physical condition as determined by medical history
• subjects must read and sign consent form

Exclusion Criteria:

• history of treatment for alcoholism, substance abuse, or drug abuse within the last 24 months
• history of malignancy, stroke, diabetes, cardiac, renal or liver disease
• history of gastroesophageal reflux disease (GERD), malabsorption syndrome, colon cancer, chronic colitis, including Crohn's disease
• history of porphyria, hyperkinesia, respiratory diseases (eg. asthma, emphysema, difficulty breathing, pulmonary obstruction)
• females who pregnant or lactating
• history of hypersensitivity to primidone, barbiturates, and anticonvulsants
• sitting systolic blood pressure below 90mm Hg, or diastolic pressure below 50mm Hg (conditions upon screening which might contraindicate or require that caution be used in the administration of primidone)
• heart rate less than 50 beats per minute after a 5 minute rest
• treatment with any other investigational drug during the four weeks prior to initial dosing
• subjects who have donated blood within four weeks prior to the initial dosing
• subjects who smoke or use tobacco products or nicotine products. Three months abstinence is required.