title: Stability of enalapril maleate in three extemporaneously prepared oral liquids.
abstract: The stability of enalapril 1 mg/mL (as the maleate) in deionized water, citrate buffer solution, and a sweetened suspending agent at two temperatures was studied. Twenty enalapril 10-mg tablets were crushed to a powder. Deionized water, citrate buffer solution, or sweetened vehicle was added to produce three 200-mL batches of each liquid; the expected final concentration of enalapril in each was 1 mg/mL. Each formulation was stored in 10 60-mL bottles, 5 of which were stored at 4 degrees C and 5 at 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for visual inspection and analysis by high-performance liquid chromatography; pH was measured at each sampling time as well. The mean concentration of enalapril in the three liquids at 4 degrees C was > 94% of the initial concentration throughout the 91-day study period. At 25 degrees C, the mean concentration of enalapril was > 90% for 56 days and > 92% for 91 days in both citrate buffer solution and sweetened vehicle. The pH of the liquid prepared with deionized water and stored at 25 degrees C decreased by 2.0 pH units. Enalapril 1 mg/mL (as the maleate) in three extemporaneously compounded oral liquids was stable for 91 days at 4 and 25 degrees C with the exception of enalapril in deionized water, which was stable for only 56 days at 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: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000737:chemistry*; D000959:Antihypertensive Agents / Q000737:chemistry*; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry; D004355:Drug Stability; D004656:Enalapril / Q000737:chemistry*; D010592:Pharmaceutic Aids / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D010592:Pharmaceutic Aids; D019343:Citric Acid; D004656:Enalapril; D002266:Carboxymethylcellulose Sodium