Medical Pharmacology

at a Glance

Michael J. Neal

Case Studies

Case 4: Hypertension

A routine blood pressure measurement at a GP surgery revealed that the patient, a 50–year–old man, had a blood pressure of 180/110. Several repeated visits confirmed these pressures. No cause was found for the hypertension although the patient smoked 20 cigarettes a day and was slightly obese.

  • (a) At this time, the patient felt perfectly well and asked why he should be worried about his blood pressure. What will you tell him?

    Correct answer:

    That his high blood pressure increases his risk of coronary artery disease, heart failure, renal failure, and stroke.

  • (b) What general advice will you give?

    Correct answer:

    Stress the importance of giving up smoking. Suggest that he loses weight by eating less and taking more exercise. Also suggest a reduction in alcohol consumption and avoidance of added salt as both of these may be contributory factors involved in his hypertension.

  • (c) What antihypertensive drug might you consider for initial therapy?

    Correct answer:

    The main drugs used to treat hypertension are the thiazides, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin-II receptor antagonists (ARAs) and calcium channel blockers (CCBs). The response to ACEIs and ARAs is often reduced in patients over the age of 55 years probably because they have lower renin levels than younger patients. Therefore, a thiazide (e.g. bendroflumethiazide) or CCB (e.g. amlodipine) would be a reasonable choice.

  • (d) After 3 months his blood pressure is still not controlled. What factors might be contributing to this failure of treatment and what should you do next?

    Correct answer:

    The most likely explanation for the failure to control the patient’s blood pressure is lack of compliance. Tactful questions may reveal that the drug selected for initial therapy has unwanted effects that the patient finds unacceptable.

    If you are convinced the patient is taking his medicine as directed, then a second drug should be added. For patients taking a thiazide or CCB, the addition of an ACEI (e.g. captopril) or ARA (losartan) is appropriate because both diuresis and vasodilatation stimulate the renin-angiotensin system and turn non–renin–dependent hypertension into renin–dependent hypertension. Some patients may require three or even four drugs to control their hypertension.

    Multidrug therapy is likely to reduce compliance but this can be improved by the use of sustained–release formulations and fixed–dose combinations (e.g. Co–zidocapt, which is captopril in combination with hydrochlorothiazide).

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