Factors Affecting the Stability of Herbal Medicines: A stability study is a routine procedure that ensures the maintenance of herbal medicines its safety, quality and efficacy throughout the shelf life.
The stability testing is used in investigating the quality of herbal products which varies with the time under the influence of environmental factors such as; temperature, humidity. light, oxygen, moisture, other ingredient or excipient in the dosage form, the particle size of the drug, microbial contamination, trace metal contamination, leaching from the container, etc. and also provide statistics for the determination of shelf lives.
Stability studies should be performed on at least three production batches of the herbal products for the proposed shelf life, which is normally denoted as long-term stability and is performed under natural atmospheric conditions.
Factors Affecting the Stability of Herbal Medicines
Table of Contents
1. Physical instability:
Herbal medicines are usually susceptible to physical instability due to the presence of impurities and reactions with the container. Microbial contamination and insect feeding affect the secondary metabolites and chemical composition of the plants. Volatile active components of herbal medicine have the problem of volatility and decreasing activity during storage for a long time.
2. Chemical instability:
- Herbal drugs are subjected to degradation during storage by hydrolysis, oxidation, crystallization, emulsion breakdown, enzymatic deterioration, and chemical reaction with the additives and excipients.
- Temperature – The rate of degradation of most chemical increase with an increase in temperature. That is why “Tropical area must be taken into consideration during the preparation of the formula of the herbal medicines.
- Moisture absorbed onto the surface of the solid drug will increase the rate of decomposition.
- The presence of enzymes in the product also increases the rate of chemical degradation.
- Light Many chemical reactions are induced by exposure to light of high energy. Autoxidation of volatile oil/fixed oil takes place and the substance becomes colored.
3. Environmental conditions:
Environmental conditions such as; altitude, temperature, rainfall, soil, storage conditions as well as different harvesting procedures, time and method of collection, manufacturing processes (selecting, drying, extracting, purifying, and genetic variability) can create variability in the product quality, stability and the concentration of active constituents.
4. Variability in the complex mixture:
Herbal formulations are the complex mixtures of different components obtained during the extraction process. Each component has variable shelf life, activity, concentration, and consistency. It creates a problem during storage conditions determination as it is not easy to determine the stability of final herbal preparation based on the activity and stability profile of a single component.
5. Drug interaction, deterioration, decomposition during storage:
Moisture content above the critical value and growth of micro-organisms in natural. products can cause the interaction of active components with the packaging material. Interaction of active components with the other ingredients of formulation such as; additives can also cause alteration in the novel drug activity.
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