Semi-solid dosage forms

With liquid and semi-solid dosage forms, the rate and the extent of desorption are influenced by the solvent system of the preparation, pH, and temperature conditions during processing and storage. If a severe problem exists, it will usually manifest itself via an outward sign, such as container collapse, product discoloration, or precipitation [14]. 

Table 5 SUPAC-SS (Semi-Solid Dosage Forms)... 

Pharmaceuticals, Mettler-Toledo GmbH, Schwerzenbach. [105f, 106f, IlOf] Schwarz, E. and Pfeffer, S. (1997). Use of subambient DSC for liquid and semi solid dosage forms—Pharmaceutical product development and quality control. J. Therm. Anal, 48, 557-67. [251]... 

Chattaraj, S.C. Kanfer, I. Release of acyclovir from semi-solid dosage forms a semi-automated procedure using a simple plexiglass flow-through cell. Int. J. Pharm. 1995, 125, 215-222. 

Boylan, J.C. The development of semi-solid dosage forms an overview. Drug Dev. Commun. 1976, 2, 320. 

Particle size and shape are important attributes of drug substances that can affect the dissolution rate, bioavailability, and the processing of oral solid dosage forms and the physical stability of semi-solid dosage forms. During manufacture of the bulk drug substance, the recrystallization conditions required to prepare a particular salt will inevitably influence the particle size and crystal habit conditions should be established early in the development program that routinely yield material with consistent characteristics. 

Primary container-closure system-related data will need to cover storage, transportation, and use. The choice of materials of construction, their description, and the ability of the container-closure system to protect from moisture and/or light will need to be considered. The compatibility of the container-closure and its contents will need to consider sorption, leaching, and safety. The performance of the container-closure system will also need to be considered in terms of dose delivery from any associated device that is to be supplied as part of the product. Container-closure components will require adequate specifications covering description, identification, critical dimensional tolerances, and test methodology (including pharma-copeial and noncompendial methods). More data are likely to be required for liquid or semi-liquid products than for solid dosage forms. In the latter, product stability data and container-closure system specifications may suffice. 

Issues relating to chemical incompatibility and instability may be less significant for solid dosage forms compared with liquid and semi-solid preparations. 

For a liquid or semi-solid pharmaceutical dosage form, it is crucial to include a preservative in the formulation. Commonly used preservatives in these systems include sodium benzoate, EDTA, sorbic acid, and parabens. A generic HPLC method is also recommended for the preservatives used in liquid formulations for routine monitoring to ensure the stability of the preservative itself and it must be validated specific to its use with the dosage form. (See chapters on Sample Preparation and Method Development.)... 

The choice of packaging for ophthalmic products will depend on the type of dosage form, such as whether it is a liquid solution/suspension or semi-solid gel or ointment. Also, choice will depend on how the product is to be used by the patient, such as whether it is intended to... 

The exact product optimisation studies to be conducted will depend on the type of ophthalmic dosage form to be developed (liquid drops, semi-solid gel/ointment or solid device). However, the dosage form type should be clearly defined from the product design evaluation and supporting preformulation studies, to enable the formulator to focus on the most relevant product optimisation studies. 

For some dosage forms, especially liquid and semi-solid ones, the study design may also need to include subzero temperatures, e.g., -10 to -20°C (freezer), freeze-thaw cycles or temperatures in the range 2-8°C (refrigerator). For certain preparations it may be important to observe the effects caused by exposure to light. 

All product characteristics likely to be affected by storage, e.g., assay value or potency, content of products of decomposition, physicochemical properties (hardness, disintegration, particulate matter, etc.), should be determined for solid or semi-solid oral dosage forms, dissolution tests should be carried out... 

Among various medicinal dosage forms, tablets account for approximately 80% of the drug delivery systems used today due to their ease of manufacture, convenience of dosing and stability compared with liquid and semi-solid approaches [ 1 ]. 

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