health - pharmacology

wegovy effects

weight-loss drug — increase feelings of satiety, reduces energy intake, affects hypothalamus & brainstem + reduction of blood glucose (treats diabetes)

wegovy chemistry

semaglutide similar to glucagon-like peptide-1 (GLP-1) analogue & GLP-1 receptor agonist

pharmacokinetics

what does the human body do with the drug

pharmacodynamics

what does the drug do with the human body

proper definition of pharmacokinetics

study of the interactions that determine the speed of onset, intensity and duration of drug action

steps in pharmacokinetics

absorption, distribution, metabolism, & elimination

absorption step

into the body and into the cells — molecule in blood stream & almost always have to cross membranes to work

how are drugs absorbed?

passive diffusion (depends on lipid solubility, area of absorption, magnitude of concentration gradient), carrier-mediated transport, endo/exocytosis, diffusion through aqueous & intracellular pores

distribution step

drug is transferred from the bloodstream (plasma) to tissues (interstitial fluid & cells)

metabolism step

when the drug is broken down and inactivated, or sometimes transformed into an active form

elimination step

excretion from the body (urine, faeces, exhalation)

factors that impact rate & degree of distribution

blood flow, capillary permeability, protein binding, & accumulation in + redistribution to other sites

protein binding in drug distribution

no pharmacological effect (e.g. albumin which buffers the effect of drugs)

apparent volume of distribution

measure for the amount of substance located outside circulation = total amount of drug in body / drug blood plasma concentration

pH partitioning

when the neutral form of the drug is absorbed then drug entrapment b/c acid ionized in basic environment, and vice versa

thiopentol effect

anaesthetic effect is terminated by redistribution of drug into adipose tissue & not through metabolism

biomagnification

increase in concentration of a substance as you go higher in the food chain

propofol characteristics

works quick, highly protein bound -- pretty well buffered in body, clinical effect very short b/c of distribution in fatty tissues

therapeutic window

range of drug dosage in which there is a positive effect AND there are no indications of poisoning

liver

major site for metabolism of drugs

outcomes of drug metabolism

production of metabolites that are less potent, more potent + persist longer, conversion from inactive pro-drug to active, toxic metabolites, or inactive metabolites that are water soluble

phase I of drug metabolism

oxidation (most important), reduction, hydrolysis (often performed by Cyt. P450)

phase II of drug metabolism

conjugation, glutathion/glucuronate, acetylation — makes drugs water soluble which make them easier to excrete

morphine

respiratory depressant

morphine side effects

hypoventilation, congestion, addiction

morphine biological half life

around 2 to 3 hours (quite long so easy to overdose)

synthetic opioid (remifentanil) side effect

hypoventilation

synthetic opioid biological half life

around 4 minutes

synthetic opioid breakdown

easily targeted by enzymes in our bodies & broken down in liver

isoenzyme of Cyt. P450

CYP3A4

CYP3A4 function

responsible for 50% of drug oxidation

blood-brain barrier

tight apposition of endothelial cells that hinders the crossing of charged molecules from the blood to cells of the brain (and the other way around)

ramipril

prodrug - converted in the liver by de-esterification into its active form ramiprilat

ramiprilat

ACE inhibitors — decreases blood pressure

ACE enzyme

in pathway that causes vasoconstriction which leads to increased blood pressure

ion trapping = weak base will accumulate in compartments with relatively ___ pH

low

ion trapping = weak acid will accumulate in compartments with relatively ___ pH

high