A pharmaceutical dosage form is a physical form of a drug, such as a solid, liquid, or gas, that is delivered in its proper form to specific sites of action within the body. The commonly used dosage forms include tablets, solutions, capsules, injections, semisolids, and aerosols they deliver the active pharmaceutical ingredient using different routes of drug administration such as oral, parenteral (Injection), topical, sublingual, and buccal.
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Semi solids are topical dosage forms intended for therapeutic, protective, or cosmetic and can be used as drug carriers that are transported topically through the skin, outer ear lining nasal mucosa, rectal tissue, buckle tissue, and cornea. Semi solids contain one or more active pharmaceutical ingredients homogeneously dispersed (dissolve) in a suitable base and any appropriate excipients. Ointments, cream, pastes, gels, rigid foams, and plasters, etc. are examples of the semi-solid dosage form.
Ideal properties of semi solids:
Various routes and dosage forms are used to make the drug more effective in which topical or semisolid formulation is ideal for the skin.
Physical properties:
Biological factors influencing skin absorption are skin condition, skin age, blood flow, region skin site, skin metabolism, and species difference, etc.
Physio-chemical factors influencing skin absorption are skin hydration, temperature and pH, diffusion coefficient, the concentration of the drug, partition coefficient, and molecular size and shape.
- It should have a smooth texture
- It should be elegant in appearance
- It should be non-dehydrating
- It should be non-gritty
- It should be non-greasy and non-staining
- It should be non-hygroscopic
- It should be non-irritating
- Do not alter membrane or skin functioning
- It should be miscible with skin secretion
- It should have a low sensitization index
- It should easily applicable with efficient drug release
- It should have a high aqueous washing ability
- Its store temperature should not exceed 25° degrees
- Should not be allowed to freeze and stored in a well-closed container
Ingredients desirable for semisolid dosage form:
- Bases
- Humectants
- Preservative
- Antioxidants
- Gelling agent
- Emulsifier
- Buffers
- Permeation enhancer
Ideal properties of the base which used in semi solids:
The base is the most essential ingredient used in the semisolid dosage form. Ointment bases not only work as carriers for pharmaceuticals, although they also regulate the amount of absorption of medicaments incorporated in them.
- It should be inert, non-irritating and non-sensitizing
- It should be compatible with the skin pH and the drug
- It should be a good solvent and/or emulsifying agent
- It should be emollient, protective, non-greasy, and easily removable
- It should release medicaments readily at the site of application
- Pharmaceutically elegant and possess good stability
Factors that affect skin penetration:
Biological and physio-chemical are the two major factors that affect the dermal penetration of the drug.
Biological factors influencing skin absorption are skin condition, skin age, blood flow, region skin site, skin metabolism, and species difference, etc.
Physio-chemical factors influencing skin absorption are skin hydration, temperature and pH, diffusion coefficient, the concentration of the drug, partition coefficient, and molecular size and shape.
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