الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
As a matter of fact, more than one-third of the drugs listed in the U.S.
Pharmacopeia classified as poorly water-soluble or water-insoluble categories. It is
commonly known in the pharmaceutical industry that an average more than 40% of
recent discovered drug candidates are poorly water soluble. Poor “drug like”
properties of these compounds led to slow absorption at the site of administration,
which has been designated as an important part of the high clinical failure due to
incomplete bioavailability, inter-subject variability and lack of dose proportionality.
Water-insoluble drugs often show low bioavailability when administered
orally, because the dissolution and absorption of the drug are a rate limiting step.
Therefore, the enhancement of the bioavailability of water-insoluble drug remains one
of the most challenging aspects of dosage form development. The therapeutic
effectiveness of a drug depends upon the ability of the dosage form to deliver the
medicament at its site of action at a rate and amount sufficient to evoke the desired
pharmacological response.
Several methods and techniques were used to improve the dissolution rate of
these drugs such as; salt formation, particle size reduction, liposomes, complexation
with cyclodextrins, nanoparticles, microemulsions, micellar solubilization, solid
dispersion and co-grinding with certain carriers.
There are several methods to reduce the size of drug particles such as
pulverization of large particles using ball mill and vibrational mill. Generally, fine
drug particles could be prepared by spray drying, rapid expansion of the supercritical
solution, grinding method and so on. The grinding method shows several advantages
such as being performed easily and environmental friendly since it requires no organic
solvents. However, grinding hydrophobic drugs usually caused the aggregation of
drug particles and consequently resulted in the limitation of size reduction and low
enhancement for oral bioavailability.