Patient leaflets and SmPCs, drug interaction checker, official and paediatric dosages, pregnancy and breastfeeding guidance, and NHS pharmacy opening hours — all in one place.
Patient leaflets and SmPCs, drug interaction checker, official and paediatric dosages, pregnancy and breastfeeding guidance, and NHS pharmacy opening hours — all in one place.
The active substance in Phentolamine mesilate 10 mg/ml solution for injection (called Phentolamine solution for injection in this leaflet) is phentolamine. It belongs to a group of medicines called alpha blockers. These medicines lower high blood pressure by relaxing blood vessels.
Phentolamine solution for injection can be used in the following cases:
• For the treatment of high blood pressure caused by a tumour of certain cells in the adrenal medulla (pheochromocytoma) before and during the surgery.
• As a test to diagnose pheochromocytoma, if other tests are not available.
Ask your doctor if you are not sure why Phentolamine solution for injection is going to be used for you.
Do not take Phentolamine solution for injection: • if you are allergic to phentolamine mesilate or any of the other ingredients of this medicine (listed in section 6).
• if you are hypersensitive to sulphite.
• if you have low blood pressure.
• if you are having a heart attack or if you have had a heart attack in the past.
• if your heart does not function properly and if you have chest tightness or any other signs of disease of the blood vessels around the heart.
Warnings and precautions Talk to your doctor or pharmacist before using this medicine:
• if you have fast or irregular heartbeats.
• if you have heartburn, abdominal pain, nausea or vomiting.
• if you have darker coloured stools or blood in your stools.
• if you have kidney impairment.
Children and adolescents This medicine can be used in children and adolescents up to 18 years of age.
Other medicines and Phentolamine solution for injection Tell your doctor or pharmacist if you are using, have recently used or might use any other medicines. This applies especially to other blood pressure−lowering medicines and medicines for the treatment of certain mental and emotional disorders.
Pregnancy and breast-feeding If you are pregnant or breast−feeding, think you may be pregnant or are planning to have a baby, ask your doctor for advice before taking this medicine. Your doctor will inform you about the benefits and risks and decide whether Phentolamine solution for injection can be used for you.
Also talk to your doctor if want to breast−feed. Phentolamine solution for injection is not advised for use in breast−feeding women.
Driving and using machines Phentolamine solution for injection may cause dizziness or other side effects. Do not drive or use machines if this happens to you. If so, contact your doctor.
Phentolamine solution for injection contains sodium metabisulphite. In rare cases, sodium metabisulphite can cause severe hypersensitivity reactions and shortness of breath due to spasm of the muscles of the airways (bronchospasm).
This medicine contains less than 1 mmol sodium (23 mg) per each 1 ml ampoule, that is to say essentially ‘sodium−free’.
This medicine is for use in hospitals and will be given by a doctor or nurse as an injection.
Your doctor will determine the dose.
Duration of the treatment Your doctor will decide the duration of the treatment.
If you are given more Phentolamine solution for injection than you should This medicine is given to you by your doctor or nurse. It is unlikely that you will be given too much. Your doctor will carefully work out how much you should be given.
If you have any further questions on the use of this medicine, ask your doctor or nurse.
Like all medicines, this medicine can cause side effects, although not everybody gets them.
Very common: (may affect more than 1 in 10 people)
• fast heart rate (tachycardia)
• low blood pressure when sitting or standing up (orthostatic hypotension)
Common: (may affect up to 1 in 10 people)
• dizziness
• sudden or prolonged periods of low blood pressure (may lead to a heart attack or stroke)
• flushing
• blocked nose
• nausea
• vomiting
• diarrhoea
• general body weakness/feeling weak (asthenia)
Uncommon: (may affect up to 1 in 100 people)
• tight, painful feeling in the chest (angina)
• abnormal heart rhythm (arrhythmia)
Reporting of side effects If you get any side effects, talk to your doctor or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
By reporting side effects you can help provide more information on the safety of this medicine.
Keep this medicine out of the sight and reach of children.
Store in the original package in order to protect from light.
Store in a refrigerator (2˚C − 8˚C).
Do not freeze.
Do not use this medicine after the expiry date which is stated on the carton after “EXP”. The expiry date refers to the last day of that month.
What Phentolamine solution for injection contains • The active substance is phentolamine mesilate. Each ampoule of 1 ml contains 10 mg phentolamine mesilate. This is equivalent to a total of 7.45 mg/ml phentolamine.
• The other ingredients are: sodium metabisulphite (E223), glucose monohydrate and water for injections.
What Phentolamine solution for injection looks like and contents of the pack Clear, colourless solution, virtually free from visible particles.
Each pack of Phentolamine solution for injection contains 5 single use ampoules of 1 ml.
Marketing Authorisation Holder and Manufacturer Marketing Authorisation Holder
ROMA Pharmaceuticals Limited
Gibraltar House
Centrum 100
Burton−upon−Trent
DE14 2WE
Email: [email protected] Manufacturer
Anfarm Hellas S.A.
61st Km National Road Athens Lamia
Schimatari
Viotias
320 09
Greece
This leaflet was last revised in August 2025.
For information in other formats contact medinfo@ romapharma.co.uk
Roma Pharmaceuticals Limited
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Phentolamine mesilate 10 mg/ ml Solution for Injection comes as solution containing 10 mg/ ml. Always follow the dose your doctor or pharmacist has given you, and read the leaflet that comes with the medicine.
The active substance in Phentolamine mesilate 10 mg/ ml Solution for Injection is phentolamine mesilate.
This leaflet reproduces the patient information leaflet approved for Phentolamine mesilate 10 mg/ ml Solution for Injection, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.
Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.
The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.
• Reversal of paroxysmal hypertension in pheochromocytoma before and during surgical treatment.
• Diagnostic phentolamine test for the identification of pheochromocytoma when other more specific tests cannot be used or have not provided sufficient results.
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. The dosage for adults is 5 mg (0.5 ml) and for children, 1 mg (0.1 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. If the blood pressure is reduced excessively, the patient should be treated as indicated in section 4.9.
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.
Intramuscular test
The dose for adults is 5 mg (0.5 ml) and for children 3 mg (0.3 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. Caution is advised when administering phentolamine mesilate to these patients (see section 4.4).
Method of administration
This medicinal product is administered intravenously or intramuscularly.
• 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.
Phentolamine mesilate may potentiate the hypotensive effect of other antihypertensive agents. Antipsychotics may potentiate the hypotensive effect of alpha-blockers.
Non-selective beta-agonists
Concomitant use of non-selective beta-agonists such as epinephrine and isoprenaline may lead to additional lowering of blood pressure. This is because adrenaline, when co-administered with phentolamine, has an effect only on the beta receptors due to blockade of the alpha receptors by phentolamine.
Pregnancy
There is very limited data on the use of phentolamine in pregnant women. Animal studies have shown reproductive toxicity (see section 5.3). Phentolamine mesilate is not recommended during pregnancy.
Breast-feeding
It is not known whether phentolamine is excreted in human milk. As a precautionary measure, breastfeeding should be discontinued during treatment with phentolamine mesilate.
Fertility
There are no available data on the effect of phentolamine on fertility in animals or humans.
Phentolamine mesilate may affect the central nervous system (see section 4.8) which may adversely affect the patients' reaction times. Therefore, patients should be advised to exercise caution when driving and using machines.
Signs and complaints
The main clinical manifestations of an overdose with phentolamine mesilate are arterial hypotension, reflex tachycardia, arrhythmias and possibly shock. These effects may be accompanied by headache, hyperexcitability and visual disturbances, sweating, vomiting and diarrhoea as well as hypoglycaemia.
Treatment
There is no specific antidote available for phentolamine overdose. It should be treated symptomatically according to the clinical condition of the patient and the judgment of the physician.
Ask anything about Phentolamine mesilate 10 mg/ ml Solution for Injection. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.
Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.
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