Pharmacology Flashcards
what is a drug?
Any agent (chemical/natural product)
that has the ability to affect living
processes
what is pharmacology?
the study of drugs including;
origin & ingredients, actions and uses
what is a drug indication?
medical/clinical condition for which the drug is meant to be used.
what are drug actions/effects?
cellular changes that occur as a result of a drug. They are varied and may include;
- depression
- stimulation
- depletion/ destruction
- biosynthesis and replacing substances
what is contraindication?
condition for which a particular drug should never be administered.
e.g. Phenytoin in pregnancy as it is a teratogenic drug
what is an adverse drug reaction?
undesired, secondary effects of drugs.
e.g. insulin may cause hypersensitivity
drug- drug interactions
drugs co-administered with other drugs may alter the desired effects of a particular medication
drug- food interactions
food co-administered with drugs may alter the desired effects of a particular medication.
what is pharmacognosy?
isolation and characterisation of drugs from natural sources.
e.g. plants, animal tissues, microbes
what are the sources of commonly used drugs?
- natural, endogenous sources
- plant sources
- microbes
- inorganic/organic elements
- minerals
- animals
- marine life
- genetically engineered drugs
- gene therapy
advantage of plants (tannins) as prescribed drugs:
- allows better control because it is free from contaminants, assures good quality and has standard packaging and formulations.
- allows better dosing because we know the exact quantity to active ingredient delivered to patient.
disadvantages of natural therapies
regulation of dose
- majority of plants drugs need precise dosing.
Different batches will have different concentrations of the active ingredients by weight.
what is an example of a drug from a microbe source
penicillin
what is an example of a drug from inorganic/organic elements
Sulphonamide is an antibacterial product of dye in mice against Staphylococcal infections
what might gene therapy be useful for?
- single gene diseases: cystic fibrosis
- certain cancers
- viral infections
- neurodegenerative diseases
what does efficacy of a drug mean?
eliciting an expected response. No effect implies no justification of using an agent.
what does specificity/ selectivity of a drug mean?
ideally, the ability to ONLY elicit pharmacological/ physiological responses for which it is administered. Drugs have specific targets for which they have a very high affinity because they do not know where to go in the body.
how to minimise safety issues of drugs?
- by appropriate dosing- if the amount of drug and the route taken into the body is appropriate, should reduce any risks
- consider agents with minimal side effects- aspirin may cause gastric bleeding and ulcers.
describe what happens to drugs once they enter the body
- drug is administered with appropriate dosage and route around body.
- ABSORPTION- rate which drug leaves administered site
- DISTRIBUTED- transport of drug in the body by bloodstream
- METABOLISM- biological transformation of a drug into an inactive metabolite
- EXCRETION- elimination of drugs from the body
how is drug administration important?
it may determine the amount of drug reaching receptors and its efficacy. It is important to determine its toxicity and therapeutic outcome on the body.
list some routes of administration into the body
- intrathecal 2. topical 3. oral 4. inhaled 5. parenteral (SC/IM/IV) 6. rectal
list some routes of administration into the body
- intrathecal 2. topical 3. oral 4. inhaled 5. parenteral (SC/IM/IV) 6. rectal
what is the definition of absorption
the rate at which a drug leaves its site of administration, and the extent to which absorption occurs (bioavailability and bioequivalent)
outline the factor of route of administration on drug ABSORPTION
depending on the route of administration will affect ifs rate of administration. inhalation and topical would be slower than oral. And parenteral (SC/IM/IV) would be faster than oral.
what is first pass effect
extensive metabolism of a drug prior to its passage from the liver into the systemic circulation (plasma).
1st pass effect is seen with orally administered drugs.
this affects the potency and efficacy of a particular drug
what is the definition of DISTRIBUTION
the transport of a drug in the body by the bloodstream to its site of action.
drugs may distribute into the plasma, interstitial fluid or ICF.
what are the factors that affect distribution
- blood flow
- dosage formulation
- capillary permeability and blood- brain barrier
where is slow distribution often seen?
in fat, skin and muscle
where are rapid areas of distribution?
heart, liver, kidney, brain
what is the blood- brain barrier?
when drugs administered to distribute to the brain, there are unique capillaries in the brain where the drug needs to pass through 2 or more membranes controlled by ion pumps.
what is drug METABOLISM?
This is the biological transformation of a drug into an inactive metabolite, a more soluble compound, or a more potent metabolite.
what are the two major phases of drug metabolism?
phase 1: conversion into lipophilic compounds
phase 2: conjugation reactions
what factors will influence drug biotransformation?
- drug- drug interactions
- genetic variability (e.g. slow vs. fast acetylators)
- disease status
- age and gender
- diet
what is drug EXCRETION?
elimination of drugs from the body. the predominant route is renal (filtration, secretion and reabsorption) and liver, bowel, lungs and skin.
what is drug clearance?
the volume of plasma from which the drug is completely removed per unit time. the amount eliminated is proportional to the concentration of the drug in the blood.
what is Elimination Half-life?
the time it takes for half the amount of the drug to be eliminated from the body.
