Pharmacokinetics Flashcards
Bioavailability Pharmacokinetics First pass effect (17 cards)
What is pharmacokinetics?
Bodys effects on the drugs, concerns how a drug gains access to the plasma, if it stays in the plasma or prefers to distribute elsewhere, metabolism an dexcreton
Are hydrophobic or hydrophilic drugs absorbed better
Hydrophobic (lipid soluble)
What is phase I of biotransformation?
Reduction or hydrolysis of the drug but most commonly oxidation.
Yields a polar, water-soluble metabolite that is often still active.
Many of the products in this phase can also become substrates for phase II
What is phase II of biotransformation?
Adding hydrophilic groups to the original molecule, a toxic intermediate or non-toxic metabolite formed in phase I that requires further transformation to increase its polarity.
What is the most common method of phase II
Glucuronidation
What is phase III of biotransformation?
Active transport of the compound into urinary or HPB system to facilitate elimination
What is first pass effect?
drug undergoes metabolism at a specific location in the body so the active drugs concentration is reduced when it reaches the systemic circulation
e.g. enters the liver and is metabolised so drug is lost
Which drugs undergo significant first pass effect?
imipramine
fluphenazine
morphine
diazepam
buprenorphine
Which drugs undergo little/no first pass effect?
lithium
pregabalin
which form of administration undergoes the most first pass effect?
oral
Which form of administration avoids first pass effect?
Sublingual
Rectal (partly avoids first pass)
Intravenous
Intramuscular
Transdermal
Inhalation
What is the difference between pharmacokinetics and pharmacodynamics?
Pharmacokinetics - what the body does to the drug
Pharmacodynamics - what the drug does to the body
What is bioavailability?
Percentage of the drug that is detected in the systemic circulation after its administration
How much does the rectal route bypass first pass metabolism and why?
2/3
rectums venous drainage is two thirds systemic and third portal
Which AP has a lower bioavailability and why?
Lurasidone as it requires food to enhance its absorption
What is distribution?
How the drug is dispersed throughout the body after absorption
Do drugs with extensive tissue distribution have longer half lives?>
YESSSSS
