Phentolamine


Thông tin thuốc gốc
Chỉ định và Liều dùng
Injection
Dermal necrosis associated with norepinephrine IV infusion
Adult: As phentolamine mesilate: Prevention: 10 mg is added to each litre of solution containing norepinephrine. Treatment of extravasation of norepinephrine: 5-10 mg (diluted in 10 mL 0.9% NaCl) is injected via local infiltration into the affected area within 12 hours.

Intramuscular, Intravenous
Diagnosis of phaeochromocytoma
Adult: Reserved for cases in which additional confirmatory test is necessary and after risks associated with use have been considered: As phentolamine mesilate: Recommended dose: 5 mg via rapid IV inj (after pressor response to venipuncture has subsided) or IM inj. Record blood pressure immediately after inj, every 30 seconds for the 1st 3 minutes, then every 1 minute for the next 7 minutes (IV inj); or every 5 minutes for 30-45 minutes (IM inj). Patient must rest in a supine position during the test preferably in a quiet, darkened room. Delay the inj until blood pressure is stabilised by monitoring every 10 minutes for at least 30 minutes. Withhold analgesics, sedatives and all other medications except for essential drugs (e.g. digitalis, insulin) for at least 24 hours and preferably 48-72 hours before the test. Refer to the detailed product or local guideline for interpretation of response.
Child: Reserved for cases in which additional confirmatory test is necessary and after risks associated with use have been considered: As phentolamine mesilate: Recommended dose: 1 mg via rapid IV inj (after pressor response to venipuncture has subsided) or 3 mg via IM inj. Record blood pressure immediately after IV inj, at 30-second intervals for the 1st 3 minutes, then at 60-second intervals for the next 7 minutes; or every 5 minutes for 30-45 minutes after IM inj. Patient must rest in a supine position during the test preferably in a quiet, darkened room. Delay the inj until blood pressure is stabilised by checking every 10 minutes for at least 30 minutes. Withhold analgesics, sedatives and all other medications except for essential drugs (e.g. digitalis, insulin) for at least 24 hours and preferably 48-72 hours before the test. Refer to the detailed product or local guideline for interpretation of response.

Intramuscular, Intravenous
Hypertension in phaeochromocytoma
Adult: As phentolamine mesilate: For prevention or control of cases: Preoperative reduction of elevated blood pressure: 5 mg via IV or IM inj given 1 or 2 hours prior to surgery, may be repeated if necessary. During surgery: 5 mg via IV inj as indicated.
Child: As phentolamine mesilate: For prevention or control of cases: Preoperative reduction of elevated blood pressure: 1 mg via IV or IM inj given 1 or 2 hours prior to surgery, may be repeated if necessary. During surgery: 1 mg via IV inj as indicated.
Hướng dẫn pha thuốc
Powder for inj: Reconstitute vial labelled as 5 mg with 1 mL sterile water for injection to a concentration of 5 mg/mL solution. For extravasation treatment: Further dilute 5-10 mg in 10 mL 0.9% NaCl.
Chống chỉ định
Existing or history of MI, coronary insufficiency, angina, other evidence suggestive of coronary artery disease.
Thận trọng
Patient with history of CV disease; gastritis or peptic ulcer. Pregnancy and lactation.
Tác dụng không mong muốn
Significant: Tachycardia, cardiac arrhythmias.
Gastrointestinal disorders: Nausea, vomiting, diarrhoea.
General disorders and administration site conditions: Weakness.
Nervous system disorders: Dizziness.
Respiratory, thoracic and mediastinal disorders: Nasal stuffiness.
Vascular disorders: Acute and prolonged hypotensive episodes, orthostatic hypotension, flushing.
Potentially Fatal: MI, cerebrovascular spasm or occlusion.
IM/IV/Parenteral: C
Chỉ số theo dõi
Monitor blood pressure, heart rate, extravasation site; signs and symptoms of orthostasis. Evaluate cardiac status.
Quá liều
Symptoms: CV disturbances (e.g. arrhythmias, hypotension, tachycardia, shock), excitation, headache, visual disturbances, sweating, pupillary contraction, nausea, vomiting, diarrhoea, and hypoglycaemia. Management: Supportive treatment. Raise the patient's leg and administer plasma expander. May give IV infusion of norepinephrine, if necessary, then titrate to maintain blood pressure at normotensive level; do not use epinephrine.
Tác dụng
Description: Phentolamine is a competitive and non-selective α-adrenergic blocker that briefly antagonises the circulating norepinephrine and epinephrine, thus reducing hypertension caused by α effects of these catecholamines and decreasing tissue injury due to extravasation of these along with other sympathomimetic vasoconstrictors. It also has positive inotropic and chronotropic effects on the cardiac muscle.
Onset: 1-2 minutes (IV); 15-20 minutes (IM).
Duration: 10-30 minutes (IV); 30-45 minutes (IM).
Pharmacokinetics:
Metabolism: Extensively metabolised in the liver.
Excretion: Via urine (approx 13% as unchanged drug). Elimination half-life: 19 minutes (IV).
Đặc tính

Chemical Structure Image
Phentolamine

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5775, Phentolamine. https://pubchem.ncbi.nlm.nih.gov/compound/Phentolamine. Accessed Sept. 24, 2021.

Bảo quản
Powder for inj: Intact vial: Store between 20-25°C. Use the reconstituted solution upon preparation; do not store the solution.
Phân loại MIMS
Thuốc trị tăng huyết áp khác
Phân loại ATC
C04AB01 - phentolamine ; Belongs to the class of imidazoline derivative agents. Used as peripheral vasodilators.
Tài liệu tham khảo
Anon. Phentolamine Mesylate. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 10/09/2021.

Anon. Phentolamine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/08/2021.

Buckingham R (ed). Phentolamine Mesilate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/08/2021.

Phentolamine Mesylate Injection (Precision Dose Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/08/2021.

Phentolamine Mesylate Injection (Tagi Pharma, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 10/09/2021.

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