PHENTOLAMINE MESILATE

Posology • Reversal of paroxysmal hypertension in phaeochromocytoma Administer 2-5 mg of phentolamine mesilate intravenously for the treatment of hypertensive crises occurring before surgery or during the induction of anesthesia, intubation, or surgical tumor removal.

This administration is repeated if necessary, while monitoring blood pressure. For children over 8 years old, the minimum effective dose is 1 mg. The dosage should be further adjusted based on the clinical condition. During surgical tumor removal as part of the treatment of phaeochromocytoma, a hypertensive crisis may occasionally occur, even if the patient has received phentolamine as premedication.

In such cases, beta-blockade may be indicated. Use a β1-selective beta blocker, such as metoprolol, administered as a slow IV injection. • Diagnostic use in phaeochromocytoma Preparation for the test Do not administer sedatives, analgesics or other medications for 24 hours and preferably not even for 48-72 hours prior to testing, except for essential medications (such as digitalis and insulin).

Do not administer antihypertensive drugs after the test until the blood pressure has returned to the untreated elevated blood pressure level. The test should not be conducted on patients with normal blood pressure. Intravenous test Procedure: 1.

Keep the patient in a reclining position throughout the entire test, preferably in a quiet darkened room. First wait until the blood pressure has stabilized (measure the blood pressure every ten minutes for at least half an hour). 2.

1 ml). 3. Insert the injection needle into the vein and wait until the effect of venipuncture on blood pressure has passed before administering the injection. 4. Then administer the injection quickly and measure the blood pressure immediately after the injection with time intervals of 30 seconds for the first 3 minutes and 60 second intervals for the next 7 minutes.

Interpretation of the test The test is most reliable in the determination of phaeochromocytoma in patients with persistent hypertension and least reliable in patients with paroxysmal hypertension. False positive results can occur in hypertensive patients without phaeochromocytoma.

The test is positive and possibly indicates a phaeochromocytoma if the blood pressure drops by more than 35 mm Hg systolic and 25 mm Hg diastolic. A typical positive response for pheochromocytoma is a decrease of 60 mm Hg systolic and 25 mm Hg diastolic.

The maximum effect is usually visible within 2 minutes after the injection. Blood pressure usually returns to pre-test levels within 15-30 minutes, but this can occur more quickly. 9. The result is considered negative if blood pressure after injection increases, remains the same or decreases by less than 35 mm Hg systolic and 25 mm Hg diastolic.

However, a negative test result does not preclude the diagnosis of phaeochromocytoma, especially in patients with paroxysmal hypertension, where false negative results are common. 3 ml). Measure blood pressure every 5 minutes for 30-45 minutes after intramuscular injection.

A positive result for phaeochromocytoma is defined as a decrease in blood pressure of 35 mm Hg systolic and 25 mm Hg diastolic, or more, within 20 minutes of administration. Special populations Renal impairment No pharmacokinetic studies have been performed with phentolamine mesilate in patients with renal impairment.

4). Method of administration This medicinal product is administered intravenously or intramuscularly.

Adverse reactions are listed according to MedDRA system organ class. Within each system organ class, adverse reactions are presented in order of decreasing seriousness. Frequency categories: very common (≥ 1/10); common (≥ 1/100 to < 1/10); uncommon (≥ 1/1 000 to < 1/100); rare (≥ 1/10 000 to < 1/1 000); very rare (< 1/10 000); frequency not known (cannot be estimated from the available data).

System Organ Class Very Common (≥ 1/10) Common (≥ 1/100 to < 1/10) Uncommon (≥ 1/1 000 to < 1/100) Rare (≥ 1/10 000 to < 1/1 000) Very rare (< 1/10 000) Not known: (cannot be established from the available data) Nervous system disorders Dizziness Cardiac disorders Tachycardia Angina pectoris, arrhythmias Vascular disorders Orthostatic hypotension Acute or prolonged hypotensive episodes (myocardial infarction, cerebrovascular spasm and cerebrovascular occlusion may occur), flushing.

Respiratory, thoracic and mediastinal disorders Nasal congestion Gastrointestinal disorders Nausea, vomiting, diarrhoea. General disorders and administration site conditions Asthenia Chest pain Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.

It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

Tachycardia and cardiac arrhythmias may occur with the use of phentolamine mesilate. Blood pressure should be monitored regularly to ensure that dosage and duration of therapy are carefully adjusted to the patient. 9). Myocardial infarction, cerebrovascular spasms, and cerebrovascular occlusion have been reported after the administration of phentolamine mesilate, usually in association with severe hypotensive episodes.

The use of phentolamine mesilate as a screening test in hypertensive patients has largely been replaced by the commonly available urinalysis of catecholamines or other biochemical tests due to their accuracy and safety. Therefore, the diagnostic use of phentolamine mesilate is not the first choice and should only be used if the other specific tests are not available.

Due to its stimulating effect on the gastrointestinal tract, including gastric acid secretion, phentolamine mesilate should be used with caution in patients with gastritis and peptic ulcers. Since no pharmacokinetic studies have been conducted in patients with renal impairment, phentolamine mesilate should be used with caution in these patients.

5 mg sodium metabisulphite in each 1 ml of solution which may rarely cause severe hypersensitivity reactions and bronchospasm. This medicinal product contains less than 1 mmol sodium (23 mg) per 1 ml, that is to say essentially ‘sodium-free’.

• Hypersensitivity to phentolamine and related compounds. • Hypersensitivity to sulphites. • Hypotension. • Myocardial infarction, history of myocardial infarction, coronary insufficiency, angina, or other evidence of coronary artery disease.