Pharmacology Flashcards
What are the key elements of pharmacology?
Study of the chemical structure of drugs
Study of drug action
Study of the effect of drugs on cells and tissues
Study of drug use to treat disease
What should you take into account when giving women medicine
Only use a medicine when the expected benefits (usually to the mother) outweigh the risks (usually to the fetus).
What is meant by pharmacokinetics?
can be defined as the effect that the body has on drugs
What are the four key pharmacokinetic stages?
ADME
Absorption
Distribution
Metabolism
Excretion
What are the types of administration’s?
Intravascular
Oral
Intramuscular
Topical
Transdermal
Mucous membranes: buccal, rectal, vaginal, inhalational.
How are most drugs absorbed?
By passive diffusion across cell membranes
What are 3 physicochemical factors?
Rate of dissolution
Lipid solubility
Degree of ionisation
How are lipid solubles drugs transported?
Pass directly through cell membranes by passive diffusion down a concentration gradient.
How are water-soluble and ionised drugs transported?
Unable to cross membrane by diffusion so require ‘special transport’
What happens to gastric and intestinal emptying times due to the 2nd and 3rd trimesters and what could thsic ause?
Emptying time is increased by up to 30-40%, which could lead to delayd absorption for some drugs.
What are the two main fluid compartments of the body?
Intracellular fluid and extracellular fluid.
What are different types of extracellular fluid?
-Intersitial fluid between cells
-Fluid in lymph
-Fluid in blood plasma.
What are different types of intracellular fluid?
-Fluid inside blood vessel endothelial cells
-Fluid inside lymph vessel endothelial cells
-Fluid inside blood cells
-Fluid inside tissue cells.
What are the main compartments of the body?
Plasma water
Intersitial water
Intracellular water
Transcellular water
fat
What are the 4 factors that influence the distribution of drugs around the body?
Blood flow
Distribution barriers
Protein binding
Volume of distribution.
What can the rate and extent of blood perfusion effect in terms of pharmacology?
affects drug distribution to organs and tissues.
What must drugs be to be able to cross the blood brain barrier?
Must be highly lipud soluble
How do most drugs cross the placenta?
Passive diffusion
What can a reduction in serum albumin concentrations result in?
Higher levels of the free fractions of some protein bound drugs
What is the difference between active and inactive drugs?
Active-free or unbound
Inactive- protein bound
WHat does drug elimination occur by?
Metabolism and excretion
What is metabolism?
The chemical conversion of the drug moleule int another chemical entity referred to as a metabolite
Metabolites can be therapeutic, ahrmful or inactive.
What is the most effective way of making a drug inactive or less actuve?
Often to render irt less fat soluble and more water soluble.
Where does most drug metabolism occur?
In the liver.
What are the two kinds of reactions involved in drug metabolism
phase 1 and phase 2
What is pahse 1 metabolism?
In the liver which makes a drug more water soluble
What happens in phase 2 metabolism?
The drug, or its phase I metabolite, is conjugated (chemically bound) to one of a number of chemical groups to create a larger, polarised molecule.
What is the most important enzyme system involved in metabolism?
Cytochrome P450
What can enzyme inducting result in?
Increased synthesis of enzymes by the liver.
What can enzyme inhibition result in?
Decreased synthesis of enzymes by the liver.
What are most drugs excreted by?
Kidney
What bodily fluids are drugs excreted in?
Urine, Bile, breast milk, breath, sweat, tears, saliva
What is meant by pharmacodynamics and what are the two effects of it?
Defined as the effect that a drug had on the body.
Therapeutic effects and side effects
What are the key receptor functions?
Bind the body’s own chemical messengers
Convert the binding event into a signal the cell ca recognise and respond to.
What is an agonist?
A drug that activates the activiy of a receptor producing a change in physiological system
What is an antagnist?
A drug that inhibitys the activity of a receptor by blocking the production of a response by an agonist.
Why are there unwanted side effects of commonly used drugs?
As no drugs are completely specific in their actions
What are pharmacodynamic interations?
Interactions between drugs which have similar or antagonistic pharmacological effects or side effects.
When do additive interactions occur?
When two drugs with the same pharmacological effect are co-administered.
When do antagonistic interactions occur?
When drugs with opposing effects are used together.
What are the mechanisms of drug actions?
-The four main targets for drug action are transport proteins, ion channels, enzymes and receptors.
-Drugs act at molecular targets to mimic or inhibit physiological actions (Coulson, 2021).
-An agonist activates a receptor and produces a physiological response.
-An antagonist blocks a receptor and inhibits a physiological action.
-Most common adverse drug reactions (ADRs) are linked to pharmacology (Coulson, 2021).
What should you consider when giving advice about medicines to a pregnant person?
Consider non-pharmacological treatments.
Only use a medicine when absolutely essential.
Consider the period of gestation and, if possible,
avoid all drugs during the first trimester.
Avoid known human teratogens.
Avoid newer drugs because usually there is little
information on their effects in pregnancy.
Avoid polypharmacy.
Where appropriate, use the lowest effective dose
for as short a period as possible.