Sterility test systems for product recovery

When presterilized, closed canister, membrane filter units for sterility testing are validated for process, large volumes of therapeutic products for injection can be tested for sterility, recovered, and added to a subsequent bulk prior to sterile filtration. Intermittent positive pressure, applied to the canisters through the vent filters, makes possible the relatively rapid filtration, with minimal foaming, of viscous solutions such as 25% (w/v) normal serum albumin (human). Canister systems appear to be at least as effective as the standard membrane filter method, and the canisters are particularly suited to the sterility testing of bulks.