PHENOXYBENZAMINE
Background and Date of Approval
Phenoxybenzamine was initially approved by the United States Food and Drug Administration (FDA) on December 11, 1953.
Uses
Phenoxybenzamine manages pheochromocytoma, a tumor that causes high blood pressure. It is also used as preoperative blood pressure stabilization before tumor removal.
How is it administered?
Phenoxybenzamine can be administered orally in the form of capsules. It is usually taken by mouth with water. A healthcare professional provides the specific dosage and administration instructions based on the individual's condition and needs.
Side Effects
Phenoxybenzamine use may lead to various side effects, including dizziness, weakness, nausea, nasal congestion, headache, and palpitations due to its impact on blood pressure and smooth muscles. More serious effects encompass severe hypotension (low blood pressure), tachycardia (rapid heart rate), orthostatic hypotension, and fluid retention.
Warnings
Phenoxybenzamine can cause dizziness and low blood pressure (hypotension). Orthostatic hypotension (sudden drop in blood pressure upon standing) can occur with this medication. It may lead to fluid retention, which can worsen heart failure symptoms.
Precautions
Avoid activities that require alertness and coordination until you understand how Phenoxybenzamine affects you. Rise slowly from lying or sitting positions to prevent sudden drops in blood pressure and dizziness. If you have a history of heart failure, consult your healthcare provider before using this medication. Monitor for signs of fluid retention, such as swelling, and report any significant weight gain.
Word of Advice
Inform your healthcare provider about your complete medical history, including any heart conditions, liver problems, kidney issues, lung disorders, and a history of low blood pressure before taking Phenoxybenzamine. Regularly monitor your blood pressure as directed by your healthcare provider. Be cautious when changing positions, especially from lying down to standing up, to avoid sudden drops in blood pressure and dizziness. Watch for signs of fluid retention, such as leg swelling or sudden weight gain, and inform your doctor if you notice any unusual changes. If you are scheduled for surgery, including dental procedures, inform your healthcare provider that you are taking this medication. Discuss dietary recommendations with your healthcare provider, especially regarding salt intake, as changes in blood pressure regulation could impact your dietary requirements. Be vigilant for signs of allergic reactions, such as rash, itching, swelling, or difficulty breathing.
References
Goodman & Gilmanâs, The Pharmacological Basis of Therapeutics, Adrenergic agonists and antagonists, 12th edition, 2011, 309. KD Tripathi, Essentials of Medical Pharmacology, Antiadrenergic drugs and drugs for glaucoma, 7th edition, 2013, 141. ADVANZ Pharma, Electronic medicines compendium (emc), [Revised on 30th Aug 2022] [ Accessed on 24th August 2023], https://www.medicines.org.uk/emc/medicine/25189/PIL/Phenoxybenzamine#gref WellSpring Pharmaceutical Corporation, US Food and Drug Administration, [Revised on March 2008] [ Accessed on 24th August 2023], https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/008708s025lbl.pdf
Frequently Asked Questions
Can I suddenly stop taking Phenoxybenzamine?
No, do not stop taking Phenoxybenzamine suddenly without consulting your healthcare provider. Stopping abruptly can lead to rebound high blood pressure.
Can Phenoxybenzamine be used for conditions other than pheochromocytoma?
Phenoxybenzamine's primary use is for managing symptoms related to pheochromocytoma. Its use for other conditions is limited due to its non-selective alpha-blocking effects.
How long does it take for Phenoxybenzamine to start working?
The onset of action can vary, but some symptom relief might be noticed shortly after starting treatment. However, achieving the full therapeutic effects can take several days or weeks.
What should I do if I miss a dose of Phenoxybenzamine?
If you miss a dose, take it as soon as you remember. However, if it's close to the time for the next dose, skip the missed dose and resume your regular dosing schedule. Do not double up on doses.
Can Phenoxybenzamine cause weight gain?
Some individuals may experience mild fluid retention while taking Phenoxybenzamine, which can lead to weight gain. Report any significant changes in weight to your healthcare provider.
Are there any long-term side effects of Phenoxybenzamine?
Long-term effects can vary. Your healthcare provider will monitor your condition and assess whether the benefits of continued treatment outweigh any potential risks.