Phentolamine
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| Image:Phentolamine.svg | |
| Phentolamine
| |
| Systematic (IUPAC) name | |
| 3-[4,5-dihydro-1H-imidazol-2-ylmethyl- (4-methylphenyl)-amino]phenol | |
| Identifiers | |
| CAS number | 50-60-2 |
| ATC code | C04AB01 G04BE05 |
| PubChem | 5775 |
| DrugBank | APRD00615 |
| Chemical data | |
| Formula | C17H19N3O |
| Mol. weight | 281.352 g/mol |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Metabolism | ? |
| Half life | 19 minutes |
| Excretion | ? |
| Therapeutic considerations | |
| Pregnancy cat. |
? |
| Legal status | |
| Routes | Usually IV or IM |
Phentolamine is a nonselective alpha-adrenergic antagonist. Its primary action is vasodilation. The primary application for phentolamine is for the control of hypertensive emergencies, most notably due to phaeochromocytoma (pheochromocytoma). It also has usefulness in the treatment of cocaine induced hypertension, where one would generally avoid beta blockers and where calcium channel blockers are not effective. In this context it is probably most safely given by infusion since bolus doses have a propensity towards causing precipitous falls in blood pressure.
When given by injection it causes blood vessels to expand, thereby increasing blood flow. When injected into the penis (intracavernosal), it increases blood flow to the penis, which results in an erection.
It may be stored in crash carts to counteract severe peripheral vasoconstriction secondary to extravasation of peripherally placed vasopressor infusions, typically of norepinephrine. Epinephrine infusions are less vasoconstrictive than norepinephrine due to their primary beta receptor stimulation before alpha but the effect remains dose dependent.
Phentolamine also has a diagnostic role in complex regional pain syndrome (reflex sympathetic dystrophy).
| Antihypertensives (C02) and diuretics (C03) edit | ||
|---|---|---|
| Antiadrenergic agents (including alpha): |
Clonidine, Doxazosin, Guanethidine, Guanfacine, Lofexidine, Mecamylamine, Methyldopa, Moxonidine, Prazosin, Rescinnamine, Reserpine | |
| Vasodilators: |
Diazoxide, Hydralazine, Minoxidil, Nitroprusside, Phentolamine | |
| Other antihypertensives: | ||
| Low ceiling diuretics: |
Bendroflumethiazide, Chlorothiazide, Chlortalidone, Hydrochlorothiazide, Indapamide, Quinethazone, Mersalyl, Metolazone, Theobromine | |
| High ceiling diuretics: | ||
| Potassium-sparing diuretics: | ||
