Introduction Flashcards
Define pharmacology
the study of drugs and their interaction with living systems
Define a drug
a substance used in the diagnosis, prevention or treatment of disease
Define pharmacokinetics
Define therapeutics
use of drugs in the prevention and treatment of disease
Define toxicology
adverse effect of the drug and the study of poisons - detection, prevention and treatment of poisoning
Sources of drugs
plant based animal mineral micro-organisms human synthetic (most drugs are synthesised)
Routes of Administration - broad divisions
- enteral (oral)
- parenteral (not oral)
- local
Advantages of enteral (oral) medications
- safest
- most convenient
- usually cheapest
- can be self administered
- non-invasive
Disadvantages of enteral (oral) medications
- slow absorption and onset of action
- irregularities in absorption
- some drugs may be destroyed by gastric juices
- irritant / unpalatable - may lead to vomiting
- can’t be given to unconscious or uncooperative patients
- patients may forget to take tablets
- some drugs undergo extensive first pass metabolism in liver
What are enteric coated tablets?
tablets coated in substances designed to minimise the disadvantages of oral medications, and to prolong the duration of action
What are the advantages of parenteral drug administration?
- action is more rapid and predictable
- can be employed in unconscious or uncooperative patients
- irritations to the GIT avoided
- can be used in patients with vomiting or those unable to swallow
- useful in emergencies
Disadvantages of parenteral drug administration
- asepsis must be maintained
- may be painful and/or case anxiety
- usually more expensive
- generally less save and less convenient
- injury to nerve and other tissue may occur
Types of parenteral routes
- injection
- inhalation
- transdermal
- transmucosal
Types of injections
- intradermal (between layers of skin)
- subcutaneous (below skin)
- intramuscular
- intravenous
- intraperitoneal - into body cavities
- intrathecal - into the spine
- intra-articular - into joints
- intra-arterial
- intramedullary (bone marrow)
advantages of inhalation
- instantaneously absorbed
- avoids metabolism in the lover
- absorbs and excretes though the lungs
disadvantages of inhalation
- irritant gases may enhance pulmonary secretions
advantages of transdermal administration
- duration of action is prolonged
- patient compliance is good
- simple self administration
- can be creams or patches
advantages of transmucosal (absorbed across mucous membrane - sublingual, nasal, rectal
- rapid absorption
- avoids liver metabolism
- sublingual drugs can be spat out to avoid unwanted side effects
disadvantages or transmucosal route
- buccal ulceration can occur
Nurse responsibilites for drug administration
- know the 6 rights
- allergy history
- monitor for adverse effects
- follow legal requirements and local policy directives
What factors impact the absorption time of a drug?
- disintegration and dissolution time
- drug formulation (eg using diluents, starch)
- particle size
- lipid solubility
- area and vascularity of absorbing surface
- gastrointestinal motility
- presence of food
- metabolism
- diseases
Define bioavailability
the fraction of the drug that reaches the systemic circulation following administration of any route
define bioequivalence
the study of comparison bioavailability of different formulations of the same drug
Where are drugs metabolised?
- liver
- kidneys
- lungs
- blood
- skin
What are the two stages of drug metabolisation?
- non-synthetic reactions: water soluble drugs metaobolite naturally
- synthetic reaction: non-soluble drugs combine with soluble substances present in the body forming compounds that can be excreted by the kidneys and through bile
Where are drugs excreted?
- kidneys
- intestine
- biliary system
- lungs
Small amounts:
- saliva
- sweat
- breast milk
Define half-life
the time taken for a drug to be reduced to half it’s value
define minimum dose
the smallest does required to produce a desired therapeutic effect
define maximum dose
the largest dose of the drug that can be safely given to a patient without producing harmful effects
define toxic dose
the dose of the drug which produces undesirable effects in a majority of people
define lethal dose
a dose of the drug which can cause death
define pharmacodynamics
the action of what drugs do, and how they do it.
drugs modify the rate of functions of various systems.
This is often termed the action of the drug
Drug actions
- stimulation
- depression
- replacement
- anti-infective
- modification
define drug synergism
when action of one drug is enhances or facilitated by another drug
define drug antagonism
when one drug opposed or inhibits the action of another drug
define drug additive effect
the individual actions of drugs are added to give a total effect
Factors modifying the drug action
- body weight
- age
- sex
- diet
- environment
- route of administration
- genetic factors
- dose
- cumulation
- disease
- tolerance
- psychological factors
Define pathophysiology
study of changes in the functioning of the body that result in disease or disorders
Define potency
the amount of chemical required to produce an effect - the lower the dose required, the more potent the drug
define selectivity
the narrowness of a drug’s range of actions on particular receptors, cellular processes or tissues
define specificity
the relationship between the chemical structure of a drug and its pharmacological actions
define “the ideal drug”
- easily administered (preferably orally)
- fully absorbed from the gastrointestinal tract
- not highly protein-bound in the blood plasma
- potent
- highly specific
- selective
- rapid onset
- useful duration of action
- high therapeutic index
- unlikely to interact with other drugs or foods
- spontaneously eliminated
- stable chemically and microbiologically
- readily formulated into easily taken form
- inexpensive
(there is no ideal drug)
What is the difference between organic and inorganic drugs?
Organic drugs contain carbon. Inorganic does not
what are the pharmacologically active constituents of plant-based drugs?
- alkaloids
- carbohydrates
- glycosides
- hydrocarbons
- oils
- phenols
- tannins
- isoprenes, terpenes and steroids
what is an alkaloid?
- organic nitrogen-containing compounds that are alkaline and usually bitter-tasting
- most alkaloids are amines, so end in suffix ‘ine
- examples include morphine, codeine, ephedrine, nicotine, caffeine
what are carbohydrates (from plant-based drugs)?
- organic compounds of carbon, hydrogen and oxygen
- source of energy
- carbohydrate gums are useful laxatives and soothing agents
- examples include glucose, cellulose, aloe vera
What are glycosides?
- a carbohydrate that, on hydrolysis, yields a sugar plus one or more additional substance
- the sugar component may aid solubility, absorption, permiability, and cellular distribution of the glycoside.
- examples include digoxin
What are hydrocarbons?
- organic molecules consisting entirely of hydrogen and carbon.
- useful for fragrances and in the formulation of creams and ointments
- examples include fats, waxes, oils and fatty acids
What are oils (from plant-based drugs)?
- subgroup of hydrocarbons
- viscous liquids
- often flammable and immiscible
- flavouring agent, scenting agent, antiseptic
- examples include eucalyptus, peppermint, castor oil
What are phenols?
- specialised type of alcohol, contains hydroxyl group
- examples incude salicylates, isoflavones, coumarins, cannabinols and hypericin
What are tannins?
- a specialised phenol
- can tan hides by precipitating proteins
- what are isoprenes, terpenes and steroids?
- plant steroids are the starting materials for many hormone drugs
- examples include carotenoids, aspirin, menthol, camphor
What is an assay?
the technique, either chemical or biological, by which the strength and purity of a drug are measured
