UNIT 2 – PHARMACOKINETICS Flashcards
first phase of drug action for ORAL medications. Oral drugs will undergo this process before absorption.
PHARMACEUTIC
how the body moves and process the drugs
PHARMACOKINETICS
- First step
- 2nd step
- 3rd step
- 4th step
- Drug Absorption
- Drug Distribution
- Drug Metabolism (biotransformation)
- Drug Excretion
drug enters the bloodstream from its site of administration
Drug Absorption
when drug is in the bloodstream
Drug Distribution
inactivate drug
- Drug Metabolism (biotransformation)
kidney
Drug Excretion
Factors affecting drug absorption.
are slower to absorb than liquid preparation, it needs to
be dissolved first into a liquid form
Solid preparations
Factors affecting drug absorption.
are readily absorbed in acidic than in alkaline environment.
Drugs
Factors affecting drug absorption.
when the drug is in stomach acid, it will pass through the stomach walls best if it is an acidic drug.
Drug solubility to cross membranes
Factors affecting drug absorption.
are readily absorbed than Non-lipid soluble drugs
Lipid soluble drugs
Factors affecting drug absorption.
biggest factor determining the concentration of a drug that penetrates the
brain.
Lipid soluble drugs are readily absorbed than Non-lipid soluble drugs
Factors affecting drug absorption.
have less gastric acidity that might affect absorption (slower)
Elderly
Factors affecting drug absorption.
do not always interfere with the
absorption of a drug, some drugs absorbed faster with the presence of food, other drugs need to ingested in an empty stomach for faster absorption.
Presence of food in the stomach
Factors affecting drug absorption.
factor associated with drug absorption that can result in incomplete absorption
Drug instability in gastric acid
3rd step - Drug Metabolism (biotransformation)– liver inactivate drug
for oral meds – may decrease drug
bioavailability
First Pass Metabolism
3rd step - Drug Metabolism (biotransformation)– liver inactivate drug
The medication is extensively metabolized in the
patient’s liver when it passes through the intestine via the portal vein
First Pass effect
Allow drug to take on particular size and shape and to enhance drug dissolution.
EXCIPIENTS
is the time it takes for the amount of drug in the body to be reduced by
half. It will help determine the frequency of drugs or dosing.
DRUG HALF-LIFE
For example: Ibuprofen 500 mg half - life is 2 hours. So after 2 hours 250 mg will
be excreted out of the body and the other 250 mg still remains active inside the
body.
Depends on drug metabolism, concentration of drug in plasma and rate of drug
elimination
determines the dosage interval
Half-life
