Stability of a formulated N-acetylcysteine capsule for prevention of contrast-induced nephropathy.

Background: N-acetylcysteine is used as prophylaxis to prevent contrast-induced nephropathy. Aim: To investigate the stability of a formulated N-acetylcysteine capsule for prevention of contrast-induced nephropathy. Method: Gelatine capsules containing N-acetylcysteine and lactose were stored at 2-8 °C, 18-25 °C and 40 °C, with and without desiccant, at ambient and high humidity (~75%). Capsule stability was assessed using high performance liquid chromatography to measure N-acetylcysteine and N,Ndiacetylcystine (breakdown product) on Days 0, 3, 7, 14, 28, 84, 168, 252, 336 and 420 of storage. Results: At 40 °C and high humidity the capsules showed severe physical degradation and hydrogen sulphide odour, and loss of N-acetylcysteine was around 30-40% by 420 days. Under all other storage conditions, the N-acetylcysteine content was stable up to 420 days (± 2% change from initial content), irrespective of humidity. The presence of desiccant did not significantly affect stability and the presence of N,N-diacetylcystine barely exceeded the European Pharmacopoeia limit of 0.5%. Conclusion: The formulated N-acetylcysteine capsule was stable for 420 days when stored at 2-8 °C, 18-25 °C and 40 °C. [ABSTRACT FROM AUTHOR]