Pharmacokinetics

What are the 4 stages of drug handling in the body

Absorption, distribution, metabolism, excretion.

Define distribution (ADME)

Movement of drug from bloodstream to tissues

Which enzyme system metabolises 70% of drugs

Cytochrome P450

Where does most drug metabolism occur

Liver

Primary organ of drug excretion?

Kidneys via urine, sometime bile

Define Theraputic Range

Blood plasma to serum concentration that will produce desired effect without toxcicity.

What happens if drug levels fall below therapeutic range?

Reduced efficacy

What happens if drug levels exceed therapeutic range?

Increased risk of toxicity

What are the 2 primary routes of drug adminstration

Enteral - via GI
Parenteral - direct to systemic circulation

Three examples of enteral routes?

Oral, buccal, rectal

Three examples of parenteral route

Intramuscular, intravenous, intrathecal

Define bioavailabilty

Proportion of administered drug reaching the systemic circulation unchanged.

What is the bioavailability of IV drugs

100%

Name 5 factors affecting bioavailability
1.
2.
3.
4.
5.

Physicochemical properties
Pharmacogenetics
Dosage form
Physiological factors
Disease states