Page 56 - MNU-PM502- Pharmaeutical Microbiology Theoritical Book

Pharm D- Clinical Pharmacy Program Third Level Pharmaceutical Microbiology& Antimicrobials (PM 502)

1- Degradation of surfactant
• Susceptibility to biodegradation depends on the chemical structure
• Anionic surfactants are generally stable due to the slightly alkaline pH of the

formulations
• Non-ionic surfactants are readily metabolized by a wide variety of
microorganisms.

2- Degradation of thickening and suspending agents

• A wide variety of are all biodegradable by extracellular enzymes such materials
as: Starch, Acacia, Dextran

• Agar is resistant to attack.
Gelatin is hydrolyzed by a wide range of commonly occurring microorganisms

3- Utilization of humectants and co-solvents
• Materials such as glycerol and sorbitol are included in some products to reduce

water loss and are usually readily metabolized unless present in high
concentrations

4-Degradation of sweetening, flavoring and coloring agents
• Sugars and other sweetening agents can act as substrates for microbial attack.

• Oral suspensions or emulsions containing sugars are liable to fermentation
with production of gas and acid which may alter the stability of the formulation.

5- Degradation of oils and emulsions
• Microorganisms do not grow in a non-aqueous environment.
• Emulsions, they may grow in the aqueous phase

• Production of lipolytic enzymes which attack the triglyceride oil component at
the oil-water interface.
• Ointments and oils are less prone to attack but spoilage may occur when these

products contain traces of condensed water or are stored in a humid atmosphere
6- Breakdown of active ingredients

• Degradation of antibiotics such as penicillin by beta-lactamases

• Microbial enzymes which degrade chloramphenicol, aspirin, phenacetin,

paracetamol, alkaloids and steroid esters have been reported.

43