Pharmacology - Drug History

Q1. Why is it important to take a careful drug history?

A: A detailed drug history is important because it helps to:

• Plan appropriate future treatment.
• Identify whether a medicine may be causing or contributing to an illness.
• Recognize possible drug interactions.
• Detect medicines that may hide important clinical signs.
• Understand whether medicines may have affected investigation results.

Q2. How can medicines mask clinical signs?

A: Some medicines can suppress the normal signs and symptoms of disease.

For example:

• Beta-adrenoceptor antagonists (beta-blockers) may prevent the usual adrenergic symptoms of acute hypoglycaemia. They may also prevent the expected tachycardia during haemorrhage.
• Corticosteroids may reduce abdominal pain and rigidity caused by a perforated abdominal organ. They can also suppress fever associated with infection.

Q3. How can medicines affect investigation results?

A: Certain medicines can alter laboratory test results and make interpretation more difficult. For example, amiodarone can affect thyroid function tests.

Aims of Taking a Drug History

Q4. What is the main aim of taking a drug history?

A: The main aim is to identify all medicines that the patient is currently taking or has stopped taking recently.

Q5. What information should be obtained for each medicine?

A: For every medicine, determine:

• The original reason or indication for starting it.
• The formulation of the medicine.
• The dose taken.
• The frequency of administration.
• The route of administration.
• How long the patient has been taking it.
• Any beneficial effects.
• Any adverse effects.
• Any known allergies.

Q6. How should you ask a patient about their regular medications?

A: Ask the patient which medicines they take regularly. It is generally better to use the word “medicines” rather than “drugs,” because some patients may associate the word “drugs” with recreational or dependent drug use.

Whenever possible, ask the patient to show you the medicine packets, bottles, or containers.

Q7. Can GP medication records or repeat prescription lists always be trusted?

A: No. GP printouts and repeat prescription forms may not accurately represent what the patient is actually taking.

Any differences between the medical record and the patient’s actual medication use should therefore be clarified.

Q8. Which medicines are commonly forgotten by patients when giving a drug history?

A: Patients may forget to mention:

• Oral contraceptive pills.
• Eye drops.

These should therefore be asked about specifically.

Recent Medication Changes

Q9. Why is it important to ask about recent medication changes?

A: Changes in medication are a common cause of adverse drug reactions. For every medicine, establish:

• How long the patient has been taking it.
• Whether the dose has recently changed.
• Whether any medicines have recently been stopped.

Q10. Why should you ask about medicines taken only when required?

A: Medicines taken “as required” can provide useful information about disease control.

For example, frequent use of an as-required bronchodilator may indicate worsening or poorly controlled asthma.

Other Medicines and Substances

Q11. What other types of medicines or substances should be included in a drug history?

A: Ask specifically about:

• Over-the-counter medicines.
• Herbal medicines.
• Alternative medicines, such as homoeopathic preparations.
• Recreational or illegal drugs.

Q12. Why is it important to ask about herbal medicines?

A: Some herbal products contain pharmacologically active substances that may cause adverse effects or interact with prescribed medicines.

Whenever possible, examine the packaging to identify the ingredients.

Q13. What should be considered when asking about recreational or illegal drug use?

A: Ask sensitively about recreational or illegal substances. During physical examination, also look for signs that may suggest their use.

Adverse Effects and Allergies

Q14. What should you ask about medication tolerability?

A: Ask whether the patient tolerates their medicines well and whether they have experienced any unwanted or adverse effects.

Serious suspected adverse drug reactions should be reported through the appropriate adverse-reaction reporting system, such as the Yellow Card system where applicable.

Q15. How else may adverse drug effects be identified?

A: Adverse effects may be detected:

• From the patient’s symptoms.
• During physical examination.
• Through laboratory or other investigation results.

For example, diuretics may cause hypokalaemia, which can be detected through serum electrolyte testing.

Q16. What should be clarified when a patient reports a drug allergy?

A: Ask about the exact reaction to determine whether it represents:

• A true allergic reaction, or
• A drug intolerance or expected adverse effect.

Supporting Safe Medication Use

Q17. Why should you ask how patients manage multiple medicines?

A: Patients taking many medicines may need systems to help them use their medicines safely and correctly.

Examples include:

• A dosette or pill-organizer box.
• Medication administration or supervision by carers.

Q18. Why is it useful to examine the patient’s actual medicines?

A: Examining the medicines can help:

• Confirm their identity.
• Check the exact dose and instructions written on the label.
• Identify errors in administration.
• Identify incorrect storage.

For example, inappropriate storage may affect medicines such as glyceryl trinitrate (GTN).

Drug Examination and Investigation

Q19. What signs related to drug administration can be examined?

A: Examination may include looking for:

• Skin puncture marks associated with injected drugs of abuse.
• Insulin injection sites.
• Correct inhaler technique.

Q20. When may plasma drug concentrations be measured?

A: Plasma drug concentrations may be measured when monitoring drug therapy, assessing toxicity, or determining whether the drug concentration is within the desired therapeutic range.

Assessing Beneficial Drug Effects

Q21. How can the beneficial effects of antihypertensive medicines be assessed?

A: Measure the patient’s blood pressure:

• While lying down.
• While standing.
• After exercise when appropriate.

Q22. What investigation may be monitored in a patient receiving treatment for gout?

A: Serum uric acid levels may be monitored to assess the effectiveness of treatment.

Q23. What test may be used to assess anticoagulant treatment?

A: Prothrombin time, often expressed using the INR for appropriate anticoagulants, may be monitored.

Q24. What investigation helps assess treatment for diabetes mellitus?

A: Blood glucose measurements can be used to assess the effectiveness of diabetes treatment.

Q25. What investigation may be used to assess treatment for anaemia?

A: Haemoglobin levels can be checked to determine whether treatment is improving the anaemia.

Q26. What investigations are useful when monitoring thyroid medication?

A: Thyroid function tests are useful when monitoring patients taking:

• Levothyroxine.
• Antithyroid medicines.

Assessing Adverse Drug Effects

Q27. What physical finding may indicate an adverse drug reaction?

A: A skin rash may indicate an adverse or allergic reaction to a medicine.

Q28. What pupil changes may occur with opioid use?

A: Opioids commonly cause pupillary constriction (miosis).

Q29. Why should blood pressure be checked in patients taking antihypertensive medicines?

A: Antihypertensive medicines may lower blood pressure excessively and cause hypotension, including postural hypotension.

Q30. Why are serum electrolytes monitored in patients taking diuretics?

A: Diuretics can alter electrolyte concentrations, including causing abnormalities such as hypokalaemia.

Q31. What signs may occur in tricyclic antidepressant overdose?

A: Possible findings include:

• Tachycardia.
• Dilated pupils.