Transcript Pharmacokinetics of Herbal Medicine

Pharmacokinetics of Herbal
Medicine
Absorption, distribution, binding,
biotransformation and extraction of
chemicals
BSCI493
March, 2008
Factors affecting drug absorption
• Physiological factors
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Molecular weight
Degree of ionization
Product formulation
Disintegration rates
• Patient factors
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Surface area for absorption
pH of gastric juices
Gastric emptying time
Bacterial colonization of GI tract
Health of individual
Drug distribution is affected by…
• The drug’s lipophilic characteristics
• Blood supply to the tissues
• Chemical composition of various tissues
and organs
Drug binding
• Nature of binding (receptor) sites
Biotransformation
• Hepatic (liver) by cytochrome P450
or
• Nonhepatic metabolism
– Blood
– Lungs
– Intestine
Pharmacogenetics
• Liver disease
• Age
• Enzyme induction and inhibition
Drug excretion (kidneys) affected by…
• Lipid solubility
• Degree of drug ionization
• Urine pH