Abstract

Purpose: To prepare ophthalmic inserts of acyclovir, a drug of choice for herpes simplex virus (HSV) Type I infections, with the aim of improving the release pattern of the drug over a period of 12 h. Methods: Inserts containing acyclovir were prepared using a water-soluble polymeric matrix of polyvinyl alcohol and methylcellulose by the film casting method. The effects of agents increasing viscosity, hydrophobic polymers and osmotic agents on the swelling and release characteristics of the inserts were examined. Differential scanning calorimetry (DSC) and stability studies of the prepared inserts stored at 25˚C for six months were also carried out. Results: The swelling study indicated that most of the formulations continued to swell for 4-6 h before losing their original shape. Almost all the additives caused an increase in drug release from the prepared formulations when compared with the standard formulation without additives. F_3, a formulation containing ethylcellulose and Carbopol 934, did not cause an increase in drug release since the drug was present in a crystalline form as shown by DSC. Storage of the prepared inserts at 25˚C for six months showed no change in the drug release profiles. Conclusion: Ophthalmic inserts containing acyclovir were successfully prepared. Both the rate and drug release profile can be easily modified with a variety of additives.


Keywords:  Acyclovir   Inserts   Swelling diameter   Differential scanning calorimetry