Phenoxybenzamine

Phenoxybenzamine is a medicine used to treat high blood pressure associated with tumor of the adrenal glands called Pheochromocytoma. Lowering blood pressure helps to prevent future heart attack and stroke. Phenoxybenzamine is given by or under the supervision of a doctor. You should take it in the dose and duration as advised by the doctor. It is important to take it even if you feel well or if your blood pressure is controlled. Most people with high blood pressure do not feel ill, but if you stop taking this medicine, your condition could get worse. Your doctor will decide the time period till which you need to take this medicine. Making some changes in your lifestyle will also help to lower your blood pressure. These may include regular exercise, losing weight, smoking cessation, reducing alcohol intake, and reducing the amount of salt in your diet as advised by your doctor. This medicine is tolerated well by most patients but it has few side effects also. Some patients may experience dizziness and sudden lowering of blood pressure on standing. Other side effects include nausea, vomiting, ejaculation disorder, and increased heart rate. Let your doctor know if these side effects bother you or do not go away. Before taking this medicine, let your doctor know if you have any heart or kidney disease. Pregnant or breastfeeding mothers should also consult their doctor before taking it. Your doctor may check your kidney function, heart rate and blood pressure at regular intervals while you are taking this medicine. Phenoxybenzamine is an alpha blocker which helps reduce blood pressure in pheochromocytoma (a tumour of the adrenal gland). It works by opposing the action of certain hormones released from the tumor that cause the blood vessels to narrow and raise blood pressure.

• Hypertension (high blood pressure)

Phenoxybenzamine covalently binds to alpha-receptors causing long lasting non-competitive inhibition of postganglionic synapses thus blocking the effects of epinephrine and norepinephrine at α1 and α2 receptors causing arterial and venous vasodilation and reflex tachycardia.

Your doctor or nurse will give you this medicine. Kindly do not self administer.

If you miss a dose of Phenoxybenzamine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Common: • Nasal congestion (stuffy nose) • Orthostatic hypotension (sudden lowering of blood pressure on standing) • Ejaculation disorder • Vomiting • Increased heart rate • Nausea • Constriction of pupil

[UNSAFE] Phenoxybenzamine may decrease alertness, affect your vision or make you feel sleepy and dizzy. Do not drive if these symptoms occur. Phenoxybenzamine is given as a drip into a vein (intravenous infusion) under the supervision of a doctor. Take it in addition to lifestyle modification with regular exercise, a balanced diet, and smoking cessation. To lower the chance of feeling dizzy or passing out, rise slowly if you have been sitting or lying down. It may cause dizziness or sleepiness. Do not drive or do anything that requires concentration until you know how it affects you. Inform your doctor if you are pregnant, planning pregnancy or breastfeeding.

CVA, recovery period (usually 3-4 weeks) after acute MI, conditions where a decrease in blood pressure may be undesirable (e.g. coronary artery disease, stroke).

Increased hypotensive and cardiac accelerating effect with stimulators of both α- and β-receptors (e.g. epinephrine).

[UNSAFE] Phenoxybenzamine may cause excessive drowsiness with alcohol.

[CONSULT YOUR DOCTOR] Phenoxybenzamine may be unsafe to use during pregnancy. Although there are limited studies in humans, animal studies have shown harmful effects on the developing baby. Your doctor will weigh the benefits and any potential risks before prescribing it to you. Please consult your doctor.

[CONSULT YOUR DOCTOR] Phenoxybenzamine is probably unsafe to use during breastfeeding. Limited human data suggests that the drug may pass into the breastmilk and harm the baby.

[CAUTION] Phenoxybenzamine should be used with caution in patients with kidney disease. Dose adjustment of Phenoxybenzamine may be needed. Please consult your doctor. Use of Phenoxybenzamine is not recommended in patients with serious kidney disease. [CONSULT YOUR DOCTOR] There is limited information available on the use of Phenoxybenzamine in patients with liver disease. Please consult your doctor.