Sterility testing• All products labeled sterile must pass the sterility test as they have ben subjected to an effective process of sterilization as per • BP recommends or as specified in the International Pharmacopoeia and USP• These tests are suitable to reveal the presence of viable forms of bacteria, fungai and yeasts in a pharmaceutical products or devices
Extraneous microorganisms should be excluded throughout the test procedure and period The sterility testing of human and veterinary products is conducted by specific procedures Test is based on assumptions that MOs grow on the provided culture medium Limitations (different organism have different nutritional requirements, temp. for growth, spores take more time to grow)
Antimicrobial precautions To avoid any accidental contamination use Laminar Flow Hood Already present Microorganisms on the product must be killed Working area should be monitored periodically both Air Surface
TheUSP sterility tests for various pharmaceutical products and devices are as follows:
Culture media Culture media should give an early and copious (abundant) growth Different types of culture media for aerobes, anaerobes and fungi are given in official books Media may be prepared as stated in official books or dehydrated mixtures may be procured and used after reconstitution as directed by the manufacturer USP (media containing L-cystein & thioglycolate both for aerobe and anaerobes, and modified Sabouraud liquid medium for moulds and yeast) e.g Fluid thioglycolate medium and Soybean-casein digest medium
Tests for culture media¢ Sterility; incubate for bacteria and fungi, and check growth in 7 days¢ Nutritive properties; inoculate with 100 viable microorganisms of each type separately, incubate. An early and copious growth indicate the nutritional properties of the medium¢ Effectiveness of media/ antimicrobial activity; prepare 2 containers of media (15, 40, 80 mL) for each MO, add preparation and inoculate with MOs. Prepare another set without preparation. Incubate, equal growth in all indicate preparation has no AM activity
AM activity is there need to be eliminated by Suitable sterile inactivating agent Dilution either the product or increasing the media Filtration
Tests for culture media If freshly prepared media are not used within 2 days, store them in the dark, preferably 2 – 25oC Finished media may be stored in unsealed containers for 10 days, provided that they are tested weekly for growth promotion If stored in sealed containers, media may be used for one year, provided that they are tested for growth promotion every 3 months
Procedure Opening of containers Clean the exterior of ampoules and closures with an antimicrobial agent, and make access to contents in a suitable manner If packed under vacuum admit sterile air Sampling Test 20 units in each medium If contents are sufficient, may be divided so that portions are added to two specified media
Methods for sterility testing¢ Membrane filtration (for aqueous, alcoholic, oily and other preparation that are miscible)¢ Direct inoculation (for concentrated preparation)
Method I (Membranefiltration) Procedure; Filters made up of esters or mixtures of esters and cellulose, pore size 0.45µm and diameter 50mm are usually used. Adjust the sterilized filter assembly and filter under aseptic conditions. Transfer membrane either directly or cut into pieces to add in culture media and incubate.(for bacteria 20-25oC, for fungi 30-35oC for 7 days)
Pre-treatment of dosage formsbefore membrane filtration Aqueous solutions; (i) moisten membrane with meat or casein peptone solution (ii) dilute sample to 100ml and filter immediately (iii) incubate for 14 days. Soluble solids; dissolve specific qty in meat or casein peptone solution, proceed as above. Oils and oily solutions; (i) low viscous filter through dry membrane (ii) dilute viscous preparations with isopropyl myristate (iii) filter using pressure or suction (iv) wash with diluent and complete as above. Ointments and creams; fatty bases are heated to 45oC & diluted by IM filter rapidly, proceed as oily solutions.
Method II (Direct inoculation) Dilute liquids 10 fold and solids 100 folds using diluent, oily preparations use emulsifying agents. Use larger volume for AM activity elimination or for concentrated solutions. Incubate for 14 days, shake oily preparations during incubation but not to anaerobes.
Interpretation of results During or at the end of incubation if no growth, test pass. If growth is observed, preserve it and repeat the test. If no growth test pass. If growth occurs, compare with first, if non distinguishable, then test fails If growth is distinguishable repeat second time taking twice the samples. If no growth test pass, if growth occurs test fails. How and qty of sample to be taken, given in table I, II, III of BP.
Tests for ophthalmicpreparations Clarity Heavy metal particles Active content determination pH Sterility Retention time