Anti Hypertensive

  Antihypertensive Drugs
A variety of blood pressure lowering medicines (antihypertensive drugs) is available in the market. Your doctor will use the most appropriate drug or a combination of drugs after considering their risks and benefits. Good blood pressure control is important for preventing cardiovascular or cerebrovascular events. In most cases, your blood pressure needs to be monitored life-long. Antihypertensive drugs may have some side effects but these can often be resolved by adjusting the dosage or changing the type of drugs. Patients are advised to follow doctor’s instructions in using the drugs and consult their doctors if they have any concerns or queries. In Hong Kong, antihypertensive drugs can only be obtained from pharmacy with a prescription. They should be used under close supervision by healthcare professionals. Antihypertensive drugs are available in different dosage forms. They include oral (e.g. tablet and capsule) and injectable (e.g. intramuscular and intravenous injection). The most widely used medications for treating hypertension includes: 
1. ACE inhibitors Angiotensin-converting enzyme (ACE) inhibitors reduce blood pressure by relaxing your blood vessels, e.g. enalapril, lisinopril, perindopril. 2. Angiotensin II receptor blockers Angiotensin II receptor blockers help relax your blood vessels which lower your blood pressure and makes it easier for your heart to pump blood,e.g. losartan, valsartan. 3. Calcium channel blockers Calcium channel blockers keep calcium from entering the muscle cells of the heart and blood vessels. This widens your arteries and reduces your blood pressure, e.g. diltiazem, nifedipine and amlodipine. 4.Diuretics Sometimes known as water pills, diuretics work by flushing excess water and salt from the body through urine, e.g. amiloride, frusemide, indapamide. 5.Beta-blockers Beta-blockers work by making your heart beat more slowly and with less force, thereby reducing blood pressure, e.g. atenolol, metoprolol, propanolol. 6.Alpha-blockers Alpha-blockers work by relaxing your blood vessels, making it much easier for blood to flow through them, e.g.doxazosin, prazosin. 7.Centrally acting antihypertensive drugs Centrally acting antihypertensive drugs, like methyldopa and clonidine, act by stimulation of alpha 2 adrenoceptors in the central nervous system which results in a reduction in sympathetic tone and a fall in blood pressure. Methyldopa may be used for the management of hypertension in pregnancy. 8.Vasodilators Vasodilators reduce blood pressure by dilatation of blood vessels, e.g. hydralazine.

Categories of drugs and Common Side Effects and Precautions

  1. ACE inhibitors

The most common side effect is a persistent dry cough. Others include dizziness, taste disturbance, and rashes


  • Not suitable during pregnancy
  • The concomitant use of potassium supplements and potassium-containing salt substitutes is not recommended
  • Angiotensin II receptor blockers

Side Effects : Dizziness, headache


  • Not suitable during pregnancy
  • The concomitant use of potassium supplements and potassium-containing salt substitutes is not recommended
  • Calcium channel blockers

Side Effects : Flushed face, headaches, swollen ankles, constipation, dizziness and tiredness


  • Avoid drinking large quantities of grapefruit juice
  • Have high fibre diet and drink plenty of fluid to reduce the side effect of constipation
  • Diuretics

Side Effects: Urinary frequency, dizziness, gastrointestinal disturbance


  • Take the tablet in the morning
  • Hypokalaemia can occur with some diuretics
  • Beta-blockers

Side Effects: Tiredness, cold hands and feet, slow heartbeat, diarrhea and nausea, sleep disturbances, nightmares


  • May trigger asthmatic attack in patients with asthma or chronic bronchitis
  • Symptoms of hypoglycaemia may be masked in diabetic patients
  • Alpha-blockers

Side Effects: Drowsiness, hypotension (notably postural hypotension), syncope, asthenia, dizziness, headache and dry mouth


  • Take first dose at bedtime to avoid postural hypotension
  • Centrally acting antihypertensive drugs

Side Effects: Headache, dizziness, dry mouth


  • May cause drowsiness, if affected, patients should not drive or operate machinery
  • Do not drink alcohol because this may worsen the side effects
  • Vasodilator

Side Effects: Headache, nausea, vomiting, tachycardia


  • Should tell your doctor if you develop symptoms of arthritis, unexplained fever or tiredness
General advice on taking antihypertensive drugs
The following should be borne in mind when taking antihypertensive drugs: Be familiar with the name and dosage of the drugs you are taking. Be cautious about their possible side effectsTake the drugs regularly as instructed by your doctor in order to have effective control of hypertension. Keep taking the same dosage of drugs even if your conditions improve unless your doctor suggested you to change your antihypertensive regime.Do not stop medication without your doctor’s instruction. Take your medicines at the same fixed time every day as far as possible. If you miss a dose, take it as soon as possible unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next dose as directed. Do not take double dosesThe drugs should not be taken with alcoholic drinks to avoid dizziness or faintingSome types of antihypertensive drugs can cause dizziness or drowsiness, usually when you first start taking your medicine or if your doctor changes your dose. If you do feel light-headed or dizzy, you should not drive or operate machinery and seek your doctor’s advice if the symptom persists.Make sure you have sufficient drug stocks for several days. Do not wait till the last minute to refill the prescription


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