Prolonged-release dosage form

The dissolution specification for prolonged-release dosage forms should cover a minimum of three points one to ensure that dose-dumping does not occur (early, typically 20-30% release), one to confirm compliance with the dissolution curve profile (around 50% release), and one to ensure that the majority of the dose has been released (often more than 80% released). The robustness of the test procedure should be considered (e.g., to temperature, pH, and rotational speed). 

To improve the therapeutic effect of a medicine, one should try to increase the absorption of the active substance. Eye ointments and eye creams stay much longer in the conjunctival sac and on the ocular surface than eye drops. Consequently the active substance is delivered during a longer period of time to the eye. Ointments or creams could be considered as prolonged release dosage forms (depot preparations) for ophthalmic use. Viscous eye drops can... 

Ph. Eur. requires for conventional release preparations that the dissolved amount of active substance from every dosage unit after 45 min should be at least 80 % of the label claim. Other requirements apply to delayed-release and prolonged-release dosage forms. 

Examples of hydrophilic binders in this category include PEGs and poloxomers, and they are preferred for immediate release dosage forms. Hydrophobic binders include fatty acids, fatty alcohols, waxes and glycerides, and they are preferred for prolonged-release formulations. 

In cases of all but intravenous adininistration, dosage forms must make the active moiety available for absorption, ie, for dmg release. This influences the bioavailabiUty and the dmg s pharmacokinetic profile. Ideally the dmg is made available to the blood for distribution and elimination at a rate equal to those processes. Through technological developments dmg product design can achieve release, absorption, and elimination rates resulting in durations of activity of 8—12 hours, ie, prolonged action/controlled release dmg products (21,22). Such products improve the compliance rate of dmg usage by patients. 

Compressed Tablets. This popular type of dosage form offers convenience, stabiUty, accuracy and precision, and good bioavadabihty of active ingredients. After the best formulation has been estabflshed, compressed tablets can be manufactured at high rates of speed on advanced equipment. Tablets can be made to achieve rapid dmg release or to produce delayed, repeat, or prolonged therapeutic action (Controlled release technology, pharmaceutical). ... 

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