Exam Notes Sample: Pharmacology Revision Notes

Model Answer

1. Pharmacokinetics and Pharmacodynamics

Pharmacokinetics describes what the body does to a drug; pharmacodynamics describes what the drug does to the body. Both underpin safe dosing decisions on the ward.

• Absorption: movement of a drug from its administration site into the bloodstream. Oral drugs undergo first-pass metabolism in the liver, which can substantially reduce the amount of active drug that reaches systemic circulation.
• Distribution: movement of a drug around the body, influenced by protein binding, lipid solubility and blood flow to individual tissues; the volume of distribution reflects how widely a drug spreads beyond the bloodstream.
• Metabolism: chiefly hepatic, via Phase I reactions (oxidation, reduction, hydrolysis) and Phase II reactions (conjugation), converting drugs into more water-soluble metabolites for excretion.
• Excretion: mainly renal; drug half-life (t½) is the time taken for plasma concentration to fall by half, and largely determines dosing frequency and the time taken to reach steady state, usually around five half-lives.
• Pharmacodynamics: the relationship between drug concentration and clinical effect, mediated through receptor agonism, receptor antagonism, enzyme inhibition or ion channel modulation; the therapeutic index compares the effective dose to the toxic dose.

2. Drug Calculations

Accurate calculation is a registration-critical skill, and numeracy questions are usually treated as pass or fail components within nursing pharmacology exams.

Always cross-check a calculated dose against the British National Formulary range for the patient’s age and weight, and query anything that falls outside the expected range before administration proceeds.

3. Common Drug Classes

Learning drugs by class rather than individually is far more efficient for exam revision, since drugs within the same class generally share a mechanism of action, common side-effect profile and similar nursing considerations.

4. Medication Safety and the Rights of Administration

• Right patient — check the name, date of birth and identification band against the prescription chart.
• Right drug — check the label three times against the prescription before administering it.
• Right dose — recalculate independently whenever the dose is unfamiliar or the calculation is complex.
• Right route — confirm the prescribed route matches the form of the drug supplied.
• Right time — administer within the trust’s acceptable time window and document accordingly.
• Right documentation — sign the chart immediately after administration, never in advance of giving the dose.
• Many curricula now add further rights, including the right to refuse and the right to education, reflecting a genuinely person-centred approach to safe administration.

5. Adverse Drug Reactions and Interactions

• Type A reactions are predictable and dose-related, essentially an extension of the drug’s known pharmacological action, such as bradycardia with beta-blockers.
• Type B reactions are unpredictable and not dose-related, and include hypersensitivity and idiosyncratic responses such as anaphylaxis.
• Pharmacokinetic interactions occur when one drug alters the absorption, distribution, metabolism or excretion of another, for example enzyme inducers reducing the effectiveness of the combined oral contraceptive pill.
• Pharmacodynamic interactions occur when two drugs produce additive, synergistic or antagonistic effects at the same or a related receptor site.
• Report suspected adverse reactions promptly via the Yellow Card Scheme and document them clearly and fully in the patient’s record.
• Therapeutic drug monitoring is required for drugs with a narrow therapeutic index, such as digoxin, lithium and gentamicin, where the gap between an effective dose and a toxic dose is small enough that routine blood-level checks are needed.

6. Routes of Administration

The route chosen affects onset of action, bioavailability and the level of nursing supervision required; enteral routes are generally slower but lower risk, while parenteral routes act faster but demand stricter aseptic technique and closer monitoring.

• Oral: convenient and non-invasive, but subject to first-pass metabolism and slower onset; unsuitable for an unconscious or vomiting patient.
• Intravenous (IV): fastest onset with 100% bioavailability, since the drug bypasses absorption entirely; carries the highest risk of rapid adverse reaction and requires careful rate control.
• Intramuscular (IM): suitable for depot preparations and drugs that would otherwise be destroyed by gastric enzymes, such as many vaccines; absorption is slower and more variable than IV administration.
• Subcutaneous (SC): used for drugs such as insulin and low-molecular-weight heparin, giving slow, sustained absorption from the fatty tissue layer.
• Topical, inhaled and rectal routes allow a more localised effect and, particularly for inhaled and rectal administration, can reduce first-pass metabolism compared with the oral route.

7. Special Populations and Dosing Considerations

• Paediatric patients: doses are almost always calculated by body weight or surface area rather than given as a standard adult dose, and organ immaturity affects both metabolism and excretion.
• Older adults: reduced renal and hepatic function, lower body water content and polypharmacy all increase the risk of accumulation and adverse effects, so a “start low, go slow” approach is standard practice.
• Renal impairment: renally excreted drugs may need dose reduction or extended dosing intervals, guided by estimated glomerular filtration rate (eGFR).
• Hepatic impairment: reduced first-pass metabolism and clotting factor synthesis can significantly increase the effect of hepatically metabolised drugs, including some anticoagulants and sedatives.
• Pregnancy and breastfeeding: teratogenic risk must always be checked before administration, and many drug information resources classify medicines by trimester-specific risk category.

8. Legal and Professional Accountability

Safe administration is underpinned by a clear legal and professional framework, and exam scenarios frequently test whether a student can identify the correct legislation or professional standard alongside the pharmacology itself.

• Medicines Act 1968 classifies medicines as general sales list, pharmacy-only, or prescription-only, governing who may supply and administer each category.
• Misuse of Drugs Act 1971 and its Regulations classify controlled drugs into schedules, each with different storage, prescribing, administration and record-keeping requirements; Schedule 2 drugs such as morphine require a controlled drugs register and a witnessed check at the point of administration.
• Patient Group Directions (PGDs) allow specified registered professionals to supply and administer named medicines to a defined group of patients without an individual prescription, subject to strict local governance.
• The NMC Code requires nurses to work within their competence, to keep clear and accurate records, and to raise concerns immediately where a prescription appears unsafe or unclear rather than administering it regardless.
• Accountability for a medication error is shared across the system, but the administering nurse remains personally responsible for checking the prescription before proceeding, regardless of who wrote it.

Exam Tips

• Show every step of a drug calculation, including units — most marking schemes award method marks even where the final figure given is incorrect.
• Learn the rights of administration thoroughly; safety-scenario questions are common and often carry pass or fail weighting within the assessment.
• Link mechanism of action to nursing observation; examiners favour answers that connect the underlying pharmacology to what you would actually monitor at the bedside.
• For interaction questions, identify whether the mechanism is pharmacokinetic or pharmacodynamic before describing the resulting clinical consequence.
• Practise timed calculation questions under exam conditions in advance, since both speed and accuracy are assessed together.
• When a scenario names a specific patient group — paediatric, older adult, renal or hepatic impairment, or pregnancy — assume the examiner wants that factor built explicitly into your answer, not treated as background detail.
• Keep the legal framework and the pharmacology linked in your revision: a question on controlled drugs is testing the Misuse of Drugs Act 1971 process as much as it is testing the drug itself.