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Shiva Kant Thakur , profile picture
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PPTX, PDF15,667 views

Selection of drug candidates cdds.pptx

The document discusses criteria for drugs to be suitable for incorporation into controlled release formulations. It states that the drug should have a half-life between 3-4 hours, not have a short half-life under 2 hours or a long half-life over 8 hours. The drug also should not have a low therapeutic index, a high conventional dose, poor water solubility, an absorption window in the GI tract, or undergo extensive hepatic first-pass metabolism. Meeting these criteria helps ensure controlled delivery is possible without the dosage form being too large or absorption efficiency being reduced.

Health & Medicine◦
Presented by : - Shiva kant Thakur . B pharma7th sem.
 A detailed knowledge of ADME characteristics of drug is essential in the design of controlled release product.  An optimum range of given pharmacokinetic parameter of a drug is necessary beyond which controlled delivery is difficult.  Criteria to be met by drug proposed to be formulated in controlled release dosage forms are as follows.
 The half life of a drug is an index of its residence time in the body.  If the drug has a short half life less than 2 hours , the dosage form may contain a prohibitively large quantity of the drug.  Drug with elimination half life of 8hrs or more are sufficiently sustained in the body.  Ideally ,the drug should have half-life of three to four hours.
 Drug with low therapeutic index are unsuitable for incorporation in controlled release formulations.  If the system fails in the body, dose dumping may occur , leading to fatalities . E.g. Digitoxin.
 If the dose of a drug in the conventional dosage is high, its suitability as a candidate for controlled release is seriously undetermined.  This is chiefly because the size of a unit dose controlled release formulation would become too big to administer without difficulty.
 Absorption of poorly water soluble drug is often dissolution rate limited.  Incorporating such compounds into controlled release formulations is therefore unrealistic and may reduce overall absorption efficiency.
 Certain drugs when administered orally are absorbed only from a specific part of GIT tract.  This part is referred to as the ’absorption window ’. Drugs exhibiting an absorption window like fluorouracil , thiazide diuretics ,if formulated as controlled release dosage from are unsuitable.
 Delivery of the drug to the body in desired concentration is seriously hampered in case of drugs undergoing extensive hepatic first pass metabolism when administered in controlled release forms.