drug stability

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DRUG STABILITY By-Nikita khandelwal M.Pharm(ceutics) 1st sem

INDEX : 

INDEX Introduction Advantages Types Stability evaluation for different formulations Shelf life estimation Overage calculation ICH guidelines

“A measure of how pharmaceutical product maintains its quality attribute over a time” : 

“A measure of how pharmaceutical product maintains its quality attribute over a time”

Stability : 

Stability The USP defines the stability of a pharmaceutical product as “ extent to which a product retains , with in specified limits, and throught out its period of storage and use i.e its shelf life, the same properties and characteristics that it possesed at the time of its manufacture”.

Stability is used to determine : 

Stability is used to determine quality of a drug substance or drug product shelf life for the drug product Recommended storage conditions

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Why stability testing is necessary- Chemical degradation may lead lowering of concentrataion of drug in dosage form toxic product may form due to degradation of active ingridients

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Advantages of stability studies Assurance to the pateint Economic consideration Legal requirements

Types of stability : 

Types of stability Chemical Physical Microbiological Therapeutical Toxicological

Stability evaluation for different formulations : 

Stability evaluation for different formulations 1.Tablets odour colour assay degradation products dissolution moisture hardness/friability.

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2. Capsules appearance (including brittleness), colour odour of content, assay, degradation products, dissolution, moisture and microbial content.

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3. Emulsions appearance (including phase separation), colour, odour, assay, pH, viscosity, microbial limits, preservative content, and mean size and distribution of dispersed globules.

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4. Oral Solutions and Suspensions Additionally for suspensions, redispersibility, rheological properties mean size and distribution of particles should be considered. 5. Oral Powders for Reconstitution moisture and reconstitution time.

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6.Metered-dose Inhalations and Nasal Aerosols appearance (including content, container, valve, and its components), Dose content uniformity labeled number of medication actuations per container meeting aerodynamic particle size distribution, microscopic evaluation, water content, leak rate, microbial limits

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7.Topical & Ophthalmic and Preparation (ointments, creams, lotions, paste, gel,solutions and non-metered aerosols forapplication to the skin) -Topical preparations clarity, colour,odour, pH, resuspendability (for lotions), consistency, viscosity, preservative and antioxidant content (if present), microbiallimits/sterility and weight loss (when appropriate).

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-Evaluation of ophthalmic or (e.g., creams, ointments, solutions,and suspensions) Sterility particulate matter, and extractable. -Evaluation of non-metered topical aerosols delivery rate, microbial limits, spray pattern, water content, and particle size

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8. Suppositories softening range, dissolution (at 37 C) Microbial limits. 9. Small Volume Parenterals (SVPs) & Large Volume Parenterals (LVPs) particulate matter, pH, sterility and pyrogen/endotoxin.

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10. Transdermal Patches in-vitrorelease rates, leakage, microbial limits/sterility, peel and adhesive forces, and the drug release rate. 11. Freeze-dried Products Appearance of both freeze-dried and its reconstituted product, assay, degradation products, pH, water content and rate of solution.

Shelf life estimation &overage calculation : 

Shelf life estimation &overage calculation

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What is shelf life ?? Shelf life (t0.9) It is defined as the time necessary for the drug to decay to 90% of its original concentration.

Accelerated analysis for chemical stability : 

Accelerated analysis for chemical stability Based on the principles of chemical kinetics Test are carried out at different elevated temperature that enables prediction of the effective life of the preparation at normal temperature

Arrhenius equation : 

Arrhenius equation Reaction rates are proportional to the number of collisions per unit time (of reactant molecules). The number of collisions increases as the temperature increases. Therefore, the reaction rate increases as the temperature increases according to Arrhenius equation.

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K = reaction rate constant A = frequency factor constant i.e maximum number of collisions at infinite temperature Ea = Energy of activation T = absolute temperature (Kelvin)

Arrhenius plot: : 

Arrhenius plot:

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1.According to the Garrett and carper “the k value for decompostion of a drug in solution at various elevated temperature are obtained by plotting some function of concentration against time”.

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Accelerated breakdown of a drug in solution at various elevated temperature

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2. The log of specific rates of decomposition are than plotted aginst the reciprocal of the absolute temperature and the resulting line are extraplotted to room temperature

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Predicting drug stability at room temperature by Arrhenius plot

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3. Free and Blythe suggested a similar method in which the fractional life period is plotted against reciprocal temperature, and the time in days required for the drug to decompose to some fraction of its original potency at R.T is obtained.

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Log plot of t90 against reciprocal temperature

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4. The log % of the drug remaining is plotted against time in days and the time for the potency to fall to 90% of the original value i.e t90 is read from the graph. The log time to 90% is then plotted against 1/T and the time at 25 degree c gives the shelf life of the product in days

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Time in days required for drug ptency at fall 90% t90 are than plotted on a log scale

Limitations of accelerated analysis : 

Limitations of accelerated analysis Carried out only at final package container Prediction is not possible at all climatic conditions Limited to the product formulations Only apply to the those which degrade with increase in temperature

Long term stability studies : 

Long term stability studies

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2 side 95% confidence limit

Overage : 

Overage It is over loading the dosage form with more drug than 100% (i.e 110% or more) to give more time to get 90% potency i.e. shelf life is longer. Rational Shelf lives are usually a maximum of 5 years and it takes a product up to 2 years to reach customer Reduced shelf lives are seen in liquid products e.g, antibiotics and ophthalmics because they are unstable in presence of moisture Some drugs are inherently unstable e.g, vitamins. Therefore, they are over loaded.

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ICH guidelines………………… : 

ICH guidelines………………… ICH stands for International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human use. Objective Harmonization of registration application within the three regions of the EU, Japan and the United States.

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ensure and assess the safety, quality and efficacy of medicines. The zone concept- The whole world is divided into 4 climatic zones in order to harmonize and simplify stablity testing:

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Stability Studies are preformed on Drug Substances Drug Products Stress Testing Selection of Batches Container Closure System Specification Testing Frequency Storage Conditions Stability Commitment Evaluation Statements/Labeling

Drug substance General case : 

Drug substance General case

Drug substances intended for storage in a freezer : 

Drug substances intended for storage in a freezer

Drug substances intended for storage in a refrigerator : 

Drug substances intended for storage in a refrigerator

Drug product general case : 

Drug product general case

Storage in refrigerator : 

Storage in refrigerator

THANK YOU : 

THANK YOU