title: Stability of pyrimethamine in a liquid dosage formulation stored for three months.
abstract: The stability of pyrimethamine in a liquid dosage formulation stored for up to three months was studies. Commercially available 25-mg pyrimethamine tablets were crushed with a mortar and pestle and mixed with a 1:1 mixture of Simple Syrup, NF, and 1% methylcellulose to yield a suspension with a pyrimethamine concentration of 2 mg/mL. The suspension was poured into 10 amber plastic and 10 amber glass prescription bottles; 5 plastic and 5 glass bottles were stored at 4 degrees C, and the remaining bottles were kept at 25 degrees C. Samples were collected at intervals up to 91 days and tested for pyrimethamine concentration by stability-indicating high-performance liquid chromatography. Pyrimethamine remained stable throughout the three-month study period under all conditions. At 4 degrees C, pyrimethamine concentrations remained above 96% of the initial concentration; at 25 degrees C, pyrimethamine concentrations remained above 91%. No substantial changes in pH were observed. Pyrimethamine was stable for at least 91 days in an oral suspension stored in plastic or glass prescription bottles at 4 or 25 degrees C.
authors.affiliation: College of Pharmacy, Ohio State University, Columbus 43210, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Nahata
authors.forename: R S
authors.initials: RS
authors.lastname: Morosco
authors.forename: T F
authors.initials: TF
authors.lastname: Hipple
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry*; D004355:Drug Stability; D008747:Methylcellulose / Q000737:chemistry; D011739:Pyrimethamine / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D008747:Methylcellulose; D011739:Pyrimethamine