propranolol

Propranolol is a beta-adrenergic blocking agent that is used for treating high blood pressure, heart pain (angina), abnormal rhythms of the heart, and some neurologic conditions. Examples of other beta-adrenergic blockers include metoprolol (Lopressor), atenolol (Tenormin), and timolol (Blocadren).

• Neurotransmitters are chemicals that are produced and released by nerves in order to communicate with each other. The released neurotransmitters attach to receptors on other cells and induce changes within the receptor-containing cells.
• Norepinephrine is a neurotransmitter that is used by the sympathetic nervous system, a portion of the involuntary nervous system.
• Nerves of the sympathetic nervous system release norepinephrine that binds to beta receptors on other cells.
• Propranolol inhibits the sympathetic nervous system by blocking the beta receptors on the nerves of the sympathetic system.
• Since stimulation of the sympathetic nervous system is responsible for increasing the rate with which the heart beats, by blocking the action of these nerves propranolol reduces the heart rate and is useful in treating abnormally rapid heart rhythms.

Propranolol also reduces the force of contraction of the heart muscle and thereby lowers blood pressure. By reducing the heart rate and the force of muscle contraction, propranolol reduces the need for oxygen by the heart muscle. Since heart pain (angina pectoris) occurs when the oxygen demand of the heart muscle exceeds the supply of oxygen, propranolol, by reducing the demand for oxygen, is helpful in treating heart pain.

The FDA approved propranolol in November 1967.

Common side effects are:

• abdominal cramps,
• diarrhea,
• constipation,
• fatigue,
• insomnia,
• nausea,
• depression,
• dreaming,
• memory loss,
• fever,
• impotence,
• lightheadedness,
• slow heart rate,
• low blood pressure,
• cold extremities,
• sore throat, and
• shortness of breath or wheezing.

Propranolol can aggravate breathing difficulties in patients with asthma, chronic bronchitis, or emphysema. In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), propranolol can cause dangerously slow heart rates, and even shock. Propranolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure.

In patients with coronary artery disease, abruptly stopping propranolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue propranolol, its dosage should be reduced gradually over several weeks.

• The recommended dose for hypertension using short acting formulations is 80-240 mg twice daily. The maximum dose is 640 mg daily.
• The usual dose using long acting formulations is 80-160 mg daily.
• The recommended dose for chest pain is 80-320 mg daily using short acting formulations and 80-160 mg daily using long acting formulations.
• The usual dose for treatment of abnormal heart rhythms is 10-30 mg 3-4 times daily of short acting formulations.
• The recommended dose for preventing migraines is 80-240 mg daily.

• Calcium channel blockers and digoxin (Lanoxin) can lower blood pressure and heart rate to dangerous levels when administered together with propranolol.
• Propranolol can mask the early warning symptoms of low blood sugar (hypoglycemia) and should be used with caution in patients receiving treatment for diabetes.
• Propranolol reduces the metabolism of thioridazine (Mellaril), increasing the concentration of thioridazine in the body and potentially causing abnormal heartbeats.

• Safe use during pregnancy has not been established. Growth retardation and congenital abnormalities have been reported in infants whose mothers received propranolol during pregnancy. Infants whose mothers received propranolol during labor have exhibited slow heart rate, hypoglycemia, and/or respiratory depression.
• Propranolol is secreted into breast milk. It should be avoided or used with caution in nursing women.

What preparations of propranolol are available?

• Tablets: 10, 20, 40, 60, and 80 mg. Capsules: 60, 80, 120, and 160 mg. Oral Solution: 20 mg/5 ml, Injection: 1 mg/ml
• Storage: Tablets and capsules should be stored at room temperature, 15 to 30 C (59 to 86 F), in a tightly closed container.