There are two types of angina, stable and unstable. Stable angina - usually due to atherosclerotic plaques in the coronary arteries - generally worsens when the patient exerts themselves and is relieved by rest, whereas unstable angina is usually due to plaque rupture and may present as new or suddenly worsening angina. The treatment of both types involves management of acute anginal pain, and long-term preventation.

Sublingual or buccal glyceryl trinitrate (GTN) is used to relieve the ischaemic pain of acute angina, and preventative medication includes beta-blockers (propranolol, acebutolol, atenolol, bisoprolol, carvedilol, labetalol, metoprolol, nadolol, oxprenolol, pindolol, timolol), long-acting nitrates (isosorbide mononitrate, isosorbide dinitrate, transdermal and modified-release GTN), calcium-channel blockers (diltiazem, verapamil, nifedipine, nicardipine, amlodipine, felodipine, nisoldipine), nicorandil and ivabradine. Agents may be used as monotherapy or in combination.

Dosage Regimen

* GTN: Sublingual sprays or buccal tablets are used when required for ischaemic angina pain. The effect is rapid but only lasts 20-30 minutes.

* Beta-blockers: Treatment usually starts with a low dose, which is increased gradually. Twice daily administration may be required, even if a modified release preparation is being used.

* Long-acting nitrates: Isosorbide mononitrate is taken in divided doses, though modified-release preparations are taken once daily, in the morning. Isosorbide dinitrate is taken in divided doses throughout the day, with modified-release preparations taken 12 hourly. Modified-release GTN is taken two to three times a day. Transdermal GTN (patch or ointment under an occlusive dressing) is usually applied once every 24 hours.

* Calcium-channel blockers: Doses vary according to the drug being used, from once to three times a day. Modified-release preparations of diltiazem and nifedipine differ in their onset and duration of action, so prescribers are advised to prescribe by brand instead of generically.

* Nicorandil and ivabradine are taken twice daily.

Patient's knowledge of the medicine's use

* GTN is used to treat acute angina attacks.

* Beta-blockers are used to manage mild to moderate stable angina.

* Nitrates are used prophylactically where beta-blockers are inappropriate.

* Calcium-channel blockers may be used where a beta-blocker is inappropriate. A rate limiting agent is usually the first choice (verapamil, diltiazem), but a dihydropyridine agent may be used instead if the patient is at risk of heart failure.

* Nicorandil is used long-term to manage angina. It is usually used as monotherapy.

* Ivabradine may be prescribed for patients who cannot take beta-blockers.

* Angina can be asymptomatic, so the patient may not realise the importance of compliance with their medication regimen. To avoid this, emphasise that the reason they are not experiencing symptoms is because the medication is working.

Is the medicine working?

* Has the patient been taking the correct dosage of their medication?

* Has the patients symptoms/condition deteriorated? If so, refer back to the prescriber.

* Is the patient taking any OTC/herbal remedies, which may interact with their medication?

Side effects

* Nitrates (prn and prophylactic) can cause flushing, headache, dizziness, tachycardia and postural hypotension. Tolerance can occur with prophylactic nitrates: ensuring there is a patch- or tablet-free interval each day usually helps.

* Beta-blockers can cause sleep disturbances, bradycardia, fatigue, coldness of the extremities and sexual dysfunction. They can also precipitate asthma and interfere with glucose tolerance, so should not be used by patients with asthma or COPD, and should be used with caution in patients with diabetes.

* Calcium-channel blockers: Common side effects include flushing, ankle oedema and headache. Sudden withdrawal can exacerbate angina. Verapamil and diltiazem can also cause bradycardia and hypotension.

* Nicorandil can cause flushing, headache, nausea, vomiting and dizziness

* Ivabradine may cause bradycardia, headache and dizziness.

Monitoring

* GTN: Ask how often a patient is using their GTN spray or tablets, as this is a useful gauge of how well controlled their angina is.

* Beta-blockers: Heart rate, blood pressure, electrolytes, urea and creatinine and clinical status should be assessed after each increment of beta-blocker therapy.

* Prophylactic nitrates: Ask whether angina symptoms are worsening as this can indicate tolerance.

* Calcium-channel blockers: Heart rate and blood pressure should be monitored regularly.

* Nicorandil: Blood pressure should be monitored.

* Ivabradine: Blood pressure and heart rate should be monitored, and the drug stopped if the heart rate drops below 50-60 beats per minute.

Lifestyle

* General "healthy heart" measures should be adopted, such as stopping smoking, losing weight, eating a diet low in fat and salt, taking regular exercise, avoiding stress and caffeine and reducing alcohol intake.

Kevin Alexander, community pharmacist, Hafod Pharmacy, Swansea / AF

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