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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

d. Poorly Soluble Drugs

▪ Poorly water-soluble drugs are increasingly becoming a problem in terms of

obtaining the satisfactory dissolution within the GIT that is necessary for good

bioavailability.

▪ It is the challenge of medicinal chemists to ensure that new drugs are not only active

pharmacologically but have enough solubility to ensure fast-enough dissolution at

the GIT.

▪ Medicinal chemists are using approaches such as:

1. Introducing ionizable groups

2. Reducing melting points

3. Changing polymorphs

4. Introducing prodrugs to improve solubility

Pharmaceutical scientists are also applying a wide range of formulation approaches

to improve the dissolution rate of poorly soluble drugs. These include:

a. Formulating in the nano-size range.

b. Formulating in a solid solution or dispersion or self-emulsifying drug delivery

system.

c. Stabilizing the drug in the amorphous form.

d. Formulating with cyclodextrins.

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