Atenolol

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Atenolol is one of the selective beta-blockers that is given initially in patients with hypertension. It lowers blood pressure by 15 to 20% in a single drug treatment. Eventually, the drug is also prescribed for chest pains related to coronary artery disease and for heart attacks. Some physicians also prescribe this for prevention of migraine headaches and tremors.

Contents

Chemical nature

Atenolol has a systematic name of (RS)-2-{4-[2-hydroxy-3-(propan-2-ylamino)propoxy]phenyl}acetamide with a molecular formula of C14H22N2O3. It was introduced in 1976 as replacement of propanolol. Like the latter, it slows down the heart and reduces its workload BUT does not cause side effects in the nervous system. Like metoprolol, it may affect beta-2 receptors in the bronchi at high doses which may cause breathing difficulties. It was once a first-line treatment for hypertension in the United Kingdom but is currently fourth-line, as newer drugs perform better than the beta-blockers. It was approved for use in the United States in 1981.

Atenolol works by blocking stimulation of adrenaline or epinephrine on the nerves of the sympathetic nervous system. Once blocked, the heart rate is reduced and strength of heart contraction is lessened. This reduces the heart's workload which decreases demand for oxygen. The decreased demand for oxygen lessens the incidence of chest pain and heart attack. The prolonged heart rate slows down blood flow and control blood pressure.

Uses and common dosages

Atenolol may be indicated for the following conditions at specific recommended doses. The prescription may vary and should be followed.

  • High blood pressure - Depending on the patient's individual response, 25 to 100 milligrams may be given daily as a single dose. It may take 1 to 2 weeks to observe full effect.
  • Chest pains - In single or divided doses, 50 to 100 milligram tablets may be given; this must not exceed 200 milligrams a day.
  • Prevention of migraine - To prevent migraine headaches, 50 to 100 milligrams may be given daily.
  • Emergency treatment of erratic heart beats Once diagnosed, 2.5 milligrams may be injected intravenously at 1 milligram per minute. It may be repeated every 5 minutes if needed but must not exceed 10 milligrams. Other doctors may opt to infuse 150 micrograms of the drug for every kilo of body weight in 20 minutes. The injection or the infusion may be repeated every 12 hours as needed. Once the heart retains its rhythm, oral dose is given at 50 to 100 milligrams per day.
  • Heart attack - The drug may be given intravenously within 12 hours after chest pain starts. Initial dose of 5 to 10 milligrams is slowly injected at a rate of 1 milligram per minute. This can be followed by an oral dose of 50 milligrams after 15 minutes. Other physicians may opt to repeat the IV dose of 50 milligrams, 10 minutes after the last injection and then give 50 mg tablets after 12 hours. Either way, the maintenance dose will be 50 milligrams every 12 hours or 100 milligrams for 6 to 9 days after the heart attack.

Drugs for oral administration must be taken with a full glass of water and at the same time each day. Blood pressure and pulse rate must be monitored regularly to make sure that the drug is working. Physical activity must be kept at a minimum. The doctor may also prescribe a low-salt, low-fat diet along with this medication.

Dosage adjustment may be applied for patients with renal problems. This medication must not be stopped abruptly, especially for people with coronary artery disease. The doses are tapered gradually for weeks before totally discontinuing treatment.

Side effects

Most side effects of atenolol are well tolerated, mild, and mostly transient. The following side effects rarely appear with the use of the drug:

  • Abdominal upset: Cramps, diarrhea/constipation, and nausea
  • Dizziness, drowsiness
  • Leg pain
  • Vision problems
  • Slow heart rate, low blood pressure

Immediate medical intervention must be given to patients taking atenolol and experiencing the following symptoms:

Precautions and contraindications

People with certain conditions must seriously reconsider the use of atenolol. Their physician may prescribe this medication only when the benefits outweigh the risks:

  • Breathing problems (asthma, bronchitis, and emphysema)
  • Heart problems (sinus bradycardia, sinus node dysfunction, heart blocks, cardiac failure, cardiogenic shock)
  • Peripheral vascular diseases.
  • Diabetes mellitus.
  • Overactive thyroid.
  • Muscle diseases (i.e. myasthenia gravis).
  • Blood circulation problems (i.e. Raynaud's syndrome)
  • Surgery
  • Pregnancy
  • Lactation

The drug may also cause interference with the common medications listed below. It is best that the prescriber must be informed when taking them with atenolol.

Availability

Local pharmacies in the Philippines may carry oral tablets in dosages of 25, 50 and 100 milligrams. Cardioten ®, Therabloc ®, and Tenormin ® are popular brands. Velorin ® is the currently available brand that is film coated. Combination products of atenolol with amlodipine are not available. Parenteral formulations (administered via the veins) of the drug are not readily available even in tertiary hospitals.

References