Define Negative Correlation

 

Semisolid dosage forms are a group of pharmaceutical formulations that have a semi-solid consistency and are used topically. They include ointments, creams, gels, pastes, and lotions.

Factors affecting dermal penetration of semisolid dosage forms include:

1. Skin type: Skin thickness, hydration, and the presence of hair follicles, sweat glands, and sebaceous glands can affect dermal penetration.

2. Formulation factors: The type of semisolid dosage form, its ingredients, and the concentration of active ingredients can affect the penetration of the formulation.

3. Application site: The location of application, such as the face, hands, or feet, can affect the penetration of the formulation.

4. Occlusion: The use of occlusive dressings or wraps can increase dermal penetration.

5. Age: The age of the patient can affect skin permeability and therefore dermal penetration.

Method of preparation of pastes :-

Pastes are semisolid dosage forms that are thicker and stiffer than creams and ointments. They are used to treat skin conditions such as eczema, psoriasis, and acne. The method of preparation of pastes involves the following steps:

1. Choose the active ingredient and excipients: The active ingredient is the drug that provides the therapeutic effect, while the excipients are the ingredients that give the paste its consistency, texture, and stability.

2. Mixing the ingredients: The active ingredient and excipients are mixed in a mortar and pestle or a mixing bowl until a homogenous mixture is obtained.

3. Addition of the vehicle: The vehicle is the liquid component that gives the paste its consistency. It is added gradually to the mixture while stirring until the desired consistency is obtained.

4. Incorporation of preservatives and other additives: Preservatives are added to prevent microbial growth, while other additives such as flavorings and fragrances can be added to improve the patient's acceptance of the paste.

5. Packaging: The paste is then packaged in suitable containers, such as tubes or jars, and labeled with the necessary information, such as the active ingredient, concentration, and directions for use.

The consistency of pastes can be adjusted by changing the ratio of the excipients to the vehicle. For example, increasing the ratio of excipients to the vehicle will result in a thicker and stiffer paste, while decreasing the ratio will result in a softer and more spreadable paste.