Drug stability factors affecting

Factors Affecting Drug Substance and Product Stability... 

The physicochemical factors affecting the absorption are lipid solubility, dissolution rate, salt from complexation, viscosity and drug stability in the GIT. 

Arakawa, T, Prestrelski, S.I, Kenny, W.C., Carpenter, IE, Factors affecting short-term and long term stabilities of proteins. Adv Drug Deliv Rev, 1993.10 1-28. 

Microbial stability is one of the factors affecting drug product reliability. Under design and interpretation of stability studies, the Center for Drugs and Biologies... 

Once good physical stability of an emulsion is insured, its commercialization mandates chemical stability of the incorporated drug and other essential components for at least 18 months. Key factors that affect the chemical stability of pharmaceutical emulsions include drug stability in oil, drug stability in aqueous media, drug concentration in oil and emulsion, phase volume ratio, droplet size, presence of excipients, and presence of air and/or peroxide radicals. As mentioned earlier, choice of appropriate antioxidant is important. 

Patel M. S., F. S. Morton, H. Seager, and D. Howard. 1992. Factors affecting the chemical stability of carboxylic acid drugs in enhanced solubility system (ESS) softgel formulations based on polyethylene glycol (PEG).Drug Development and Industrial Pharmacy, 18 1-19. 

Nguyen NAT, Wells ML, Cooper DC. Identification of factors affecting preservative efficacy and chemical stability of lamivudine oral solution through statistical experimental design. Drug Dev Ind Pharm 1995 21 1671-1682. 

Highly disperse silica is widely used in pharmaceutical formulations as a filler, adsorbent, thickener etc.5 Their high hydrophilicity and the absence of emulsifying ability restrict their application. In contrast to hydroxylated silica, partially or fully hydrophobized silica may exhibit improved properties as a drug carrier. The main goal of this work is to study hydrophobized silica nanocomposites with immobilized vitamins C and E. Investigations of adsorption-desorption processes which involve silica nanoparticles and the antioxidants are described. Factors affecting the antioxidant stability have also been carefully considered. 

T. Arakawa, S. J. Prestrelski, W. Kinney, and J. F. Carpenter, Factors affecting shortterm and long-term stabilities of proteins. Advanced Drug Delivery Rev. 70.-1-28 (1993). 

Rabasco AM, Caraballo I, Fernandez-Arevalo M. Formulation factors affecting thimerosal stability. Drug Dev Ind Pharm 1993 19 1673-1691. 

A descriptor rate constant for solid-state degradation can be obtained once a theoretical rate equation has been derived and the data have been tested to see if they conform to the proposed model. However, for solid-state degradation in which the factors affecting the degradation mechanism have not been elucidated, because of the complexity involved, often an apparent constant (or constants) obtained by fitting the observed degradation curve to an empirical equation or equations is utilized. Such constants and the empirical relationships themselves can sometimes be used for stability prediction purposes. This section first discusses various theoretical equations used to describe the solid-state stability of drugs and introduces an empirical equation that can often describe the data adequately. 

Temperature is one of the primary factors affecting drug stability. The rate constant/ temperature relationship has traditionally been described by the Arrhenius equation,... 

Another factor affecting drug stability is electrical current. The stability of hydrocortisone hemisuccinate and phosphate esters as their sodium salts was affected by a change in pH that occurred when current was applied during an iontophoresis study.506 Degradation of propranolol hydrochloride in an electrically modulated drug delivery device has been reported.507... 

A. D Emanuele and J. N. Staniforth, An electrically modulated (hug delivery device. III. Factors affecting drug stability during electrophoresis, Pharm. Res. 9, 312-315(1992). 

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