Pharmacology is the science of drugs and how they act, including the search for new drugs, investigations into how they can best be used to treat disease, and their effects on the body.
I learnt what pharmacokinetics and pharmacodynamics are. Pharmacokinetics refers to what the body does to the drugs. That is:
– Absorption, distribution, metabolism, and excretion.
– Bioavailability
– Therapeutic range
– Half-life
– Peak-plasma concentrations
Pharmacodynamics – what the drugs do to the body:
– The drugs acting at receptors
– The drugs acting on enzymes
– The drugs acting on transporters.
With all the above explanation, pharmacology is defined as the science that examines the composition, effects, and uses of drugs.
Pharmacology is how the body process the drugs and it is broken down into four stages:
– Absorption – how the medication will get in?
– Distribution – where will the medication go? Transporters.
– Metabolism – how is it broken down? liver
– Excretion- how does the medication leave the body?
The route of medication is categorised into 3:
– Enteral, through the gastrointestinal tract, through the portal circulation and through the liver (oral, sublingual, buccal or rectal route)
– Parental, through IV, IM, or subcutaneous administration.
– Topical, application of a medication directly to a site, (cream, inhalations, oral rinses)
The first metabolism: the absorbed drugs then pass directly to the liver via hepatic portal vein.
Any drug taken orally will reach the liver first before reaching the systemic circulation.
A large proportion of oral drugs will be chemically altered during this ‘FIRST PASS’ through the liver.
Little drug may reach the systemic circulation.
The following are the routes that avoid first pass metabolism:
– Sublingual
– Intravenous
– Intra-muscular
– Subcutaneous
– Transdermal patches
– Rectal suppositories,
– Buccal
The distribution is the process of dispersion or dissemination of drugs throughout the fluids and tissues of the body.
Drugs are not evenly distributed through tissue and fluids.
– Fat soluble drugs will concentrate in adipose tissue
– Water soluble will concentrate in the body water.
Blood –brain barrier prevents many drugs from crossing.
Metabolism is the process which biochemically changes the drug molecule into a different form, which may be active, inactive, or more soluble.
It occurs mainly in the liver.
Metabolism converts the molecule into a water –soluble substance that is readily excreted.
More soluble substances can be excreted more readily.
The excretion is the removal of waste products from the body.
The main organs of excretion are the kidneys, although the liver and the gut also pass through the process of filtration, reabsorption, and active secretion in the renal tubules and are then excreted in the urine.
Some other drugs are excreted into the biliary system of the liver and pass into the small intestine in bile, these are then passed into faeces.
In maintaining therapeutic concentration, the following should be considered:
– To maintain concentrations within the therapeutic range, repeated doses are administered to ensure that concentration rises and remains within the zone as the successive doses overlap.
– The timing of these doses is decided by the half-life of the drug.
– Half-life: the time taken for the plasma concentration of the drug to fall by half as it is distributed through the body and then metabolised or excreted from the body.
The following that affects pharmacokinetics:
– Disturbances of the gastrointestinal tract (vomiting, diarrhoea)
– Circulatory disorders
– Liver disorders
– Kidney disorders
– Interaction between drugs that can affect their activity in the body.
We looked at pharmacodynamics- what the drugs do to the body: the study of biochemical and physiological effects on the body. The 2 common binding sites for drugs:
– Receptors
– Enzymes.
These are the drugs acting at receptors:
– Many drugs’ receptors are protein molecules on the cell surface.
– The drug molecule must be the specific size and shape to interact with the precise receptor lock and key)
The drugs that acting at receptors are as follows:
Agonist:
– Chemical that binds to a receptor and activates it to produce a response.
– Most drugs acting at receptors are agonists.
Antagonist:
– Chemical that binds to a receptor but does not produce a response.
– Block the receptor so that an agonist cannot exert its effect.
Partial agonist:
– Chemical that binds to a receptor to produce a response but has less than maximum impact.
Drugs acting on enzymes – enzymes are chemicals that speed up chemical reactions within cells.
Some drugs act as enzyme inhibitors by binding to the enzyme to decrease its activity.
KSB ADDRESSED.
KNOWLEDGE.
K10: Understand the principles of epidemiology, demography, and genomics and how these may influence health and well-being outcomes.
K11: Understand the factors that may lead to inequalities in health outcomes.
K15: Understand human development from conception to death, to enable delivery of person-centred safe and effective care.
K16: Understand body systems and homeostasis, human anatomy and physiology, biology, genomics, pharmacology, social and behavioural sciences as applied to delivery of care.
K17: Understand commonly encountered mental, physical, behavioural, and cognitive health conditions as applied to delivery of care.
K22: Know how to meet people’s needs related to nutrition, hydration and bladder and bowel health.
K23: Know how to meet people’s needs related to mobility, hygiene, oral care, wound care, and skin integrity.
K24: Know how to support people with commonly encountered symptoms including anxiety, confusion, and pain.
K28: Understand the effects of medicines, allergies, drug sensitivity, side effects, contraindications, and adverse reactions.
SKILLS
S1: Act in accordance with the Code: Professional standards of practice and behaviour for nurses, midwives, and nursing associates (NMC, 2018), and fulfil all registration requirements.
S17: Protect health through understanding and applying the principles of infection prevention and control, including communicable disease surveillance and antimicrobial stewardship and resistance.
BEHAVIOUR
B1: Treat people with dignity, respecting individual’s diversity, beliefs, culture, needs, values, privacy, and preferences.
B2: Show respect and empathy for those you work with, have the courage to challenge areas of concern and work to evidence based best practice.
B3: Be adaptable, reliable, and consistent, show discretion, resilience, and self-awareness.