Pharmacology Exam Ib

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Factors controlling extent and speed of distribution of drugs
- Blood profusion of various organs
- Binding of drug to proteins in blood
- The nature of capillaries
- Mechanisms of drug transport with in the target organ
Organs with high blood profusion
- Brain
- Kidney
- Liver
- Lungs
Organs with poor blood profusion
- Skeleton
- Fat
Organs with mid-level profusion

Skeletal muscle
Proteins in plasma that bind drugs
- Albumin
- Alpha 1 acid glycoproteins
Albumin
- 50% of proteins in plasma
- affinity to bind weak acid drugs
Alpha 1 acid glycoproteins
- Affinity for weak base drugs
- much less abundant than albumin
Organs with Leaky capillaries
- better drug delivery
- kidney
- liver
Organs with tight capillaries
- Poor drug delivery
- Brain
Intersticial Transport Mechanisms
- Conductive = drug travels well
- Non-conductive = drug will not travel well
Free drug in blood reflects
- free drug in organs
- Free drug in circulation is in equillibrium with drug in organs
Malnutrition
- Lowered proteins in the body
- Lower binding of weak acid drugs to albumin
- Increased free drug concentration in circulation
- More drug distribution
Fasting for a long period of time

lowered proteins
Free Fatty Acids from diet
- Bind albumin
- Compete with weak acid drug for binding
- May result in a higher free drug concentration if fatty acid has a higher affinity for albumin than drug
Effects of aging on distribution of drugs
- Decreased plasma albumin
- Increased Alpha 1 Acid Glycoproteins
- Decreased body water
- Decreased lean body mass
Decrease in albumin

more weak acid drug distribution
Increased alpha 1 acid glycoproteins

lower distribution of weak base drugs
Decreased body water

less opportunity for drug to disperse resulting in higher drug concentrations in the body.
Decreased lean body mass
- increased fat
- lipid soluble drugs hide in fat
Drug Metabolism
- Alteration in chemical structure of a drug
- Enzymatic or non-enzymatic
Purpose of drug metabolism
- Make the drug less lipid soluble and more water soluble
- Promote excretion
What happens to a drug when it is metabolized
- Pharmacological activation
- Pharmacological inactivation
- Toxification
- Detoxification
- A combination of any of the above
Pharmacological activation
- Prodrug -> Drug
- Not the most common
Pharmacological inactivation

Most drugs are rendered inactive when they are metabolized.
Toxification

body changes a harmless entity into a harmful entity
detoxification

most common
Liver

Major organ of metabolism
Hepatocytes
- Major cells of metabolism in the liver
- Nucleus
- Mitochondria
- Endoplasmic Reticulum
- Cytosol
Microsomes

Endoplasmic Reticulum
Phase 1 Metabolic Reactions
- First wave of reactions to which the drug is subject
- Drugs may bypass phase 1 and go directly to phase 2
- Reduction
- Hydrolysis
- Dehalogenation
- Oxidation
Microsomal Oxidation Reactions
- Side chain hydroxylation
- Aromatic hydroxylation
- O-Dealkylation
- N-Dealkylation
- S-Dealkylation
- Sulfoxidation
Non-microsomal oxidation reactions

Enzymes present in every other cell compartment
Phase 2 Metabolic Reactions
- Further metabolism
- Increase solubility
- Decrease lipid solubility
- Synthetic Reactions
- Conjugation Reactions

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Card Set

Pharmacology Exam Ib

Description

Pharmacology

Updated

2010-09-01T20:11:12Z

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