- Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No Parkinson's disease No convulsions or epilepsy requiring treatment No lactose intolerance or allergy to milk products No history of allergic sensitization following administration of folic acid, pyridoxine (vitamin B6), or cyanocobalamin (vitamin B12) No vitamin B12 concentration below lower limit of normal (150 picamole/L) No untreated hypothyroidism or psoriasis