2. Materials and methods
The latex solution used consisted of a mixture of a noncontrolled
variety of clones extracted from Hevea brasiliensis, which was kindly
provided by ESALQ-USP, Piracicaba, Brazil. After extraction, ammonia
was used to keep the latex liquid, and this material was centrifuged at
8000 g. Metronidazole (MET, C6H9N3O3) was purchased from BIOFLORA
Pharmaceutics Ltd., Brazil. MET was incorporated by mixing
2 mL of natural rubber latex with 1 mL of MET solution (10 mg mL−1).
These membranes were prepared by pouring the latex+MET solution
in a stainless steel plate with 5.00±0.05 cm diameter and 234.40±
5.00 μm thick. Typically the membranes were left for 2 days to fully
polymerize before use. For the study of the release of MET, two latex
membranes were placed in 200 mL of an aqueous solution, from
which aliquots were collected during an interval ranging from 10 to
24,000 min.