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Phentolamine

 

 
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Phentolamine
 
 
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Phentolamine (Regitine) is a reversible nonselective alpha-adrenergic
Adrenergic

An adrenergic is a medication, or other substance, which has effects similar to, or the same as, epinephrine . Thus, they are a kind of sympathomimetic agents....
 antagonist
Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a Receptor , but blocks or dampens agonist-mediated responses....
.

primary action is vasodilation
Vasodilation

Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins....
 due to a1 blockade.

It also can lead to reflex tachycardia
Tachycardia

The word tachycardia comes from the Greek words tachys and kardia .Tachycardia typically refers to a heartrate that exceeds the range of the normal resting heartrate, based upon age:...
 because of hypotension and a2 inhibition, which increases sympathetic tone.

primary application for phentolamine is for the control of hypertensive emergencies
Hypertensive emergency

A hypertensive emergency is severe hypertension with acute impairment of an organ system and the possibility of irreversible organ-damage. In case of a hypertensive emergency, the blood pressure should be lowered aggressively over minutes to hours with an antihypertensive agent....
, most notably due to phaeochromocytoma (pheochromocytoma
Pheochromocytoma

A phaeochromocytoma is a neuroendocrine tumor of the Adrenal medulla of the adrenal glands , or extra-adrenal chromaffin tissue that failed to involute after birth and secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine....
).

It also has usefulness in the treatment of cocaine
Cocaine

Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine....
 induced hypertension, where one would generally avoid beta blockers and where calcium channel blockers are not effective.






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Phentolamine (Regitine) is a reversible nonselective alpha-adrenergic
Adrenergic

An adrenergic is a medication, or other substance, which has effects similar to, or the same as, epinephrine . Thus, they are a kind of sympathomimetic agents....
 antagonist
Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a Receptor , but blocks or dampens agonist-mediated responses....
.

Mechanism

Its primary action is vasodilation
Vasodilation

Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins....
 due to a1 blockade.

It also can lead to reflex tachycardia
Tachycardia

The word tachycardia comes from the Greek words tachys and kardia .Tachycardia typically refers to a heartrate that exceeds the range of the normal resting heartrate, based upon age:...
 because of hypotension and a2 inhibition, which increases sympathetic tone.

Uses

The primary application for phentolamine is for the control of hypertensive emergencies
Hypertensive emergency

A hypertensive emergency is severe hypertension with acute impairment of an organ system and the possibility of irreversible organ-damage. In case of a hypertensive emergency, the blood pressure should be lowered aggressively over minutes to hours with an antihypertensive agent....
, most notably due to phaeochromocytoma (pheochromocytoma
Pheochromocytoma

A phaeochromocytoma is a neuroendocrine tumor of the Adrenal medulla of the adrenal glands , or extra-adrenal chromaffin tissue that failed to involute after birth and secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine....
).

It also has usefulness in the treatment of cocaine
Cocaine

Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming 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
Infusion

An infusion is the outcome of Wikt:steep plants with a desired flavour in water or edible oil.An infusion is very similar to a decoction but is used with herbs that are more volatile or dissolve readily in water, or release their active ingredients easily in oil....
 since bolus
Bolus (medicine)

In medicine, a bolus is the administration of a medication, drug or other compound that is given to raise blood concentration to an effective dose....
 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 cart
Crash cart

A crash cart or code cart is a set of trays on a wheeled cart that is used in hospital wards and emergency rooms. It contains all the basic equipment necessary to follow Advanced cardiac life support/Advanced life support protocols and potentially save someone's life....
s to counteract severe peripheral vasoconstriction secondary to extravasation
Extravasation

Extravasation is the accidental administration of intravenous infused medicinal drugs into the surrounding tissue, either by leakage , or direct exposure ....
 of peripherally placed vasopressor infusions, typically of norepinephrine
Norepinephrine

Norepinephrine or noradrenaline is a catecholamine with dual roles as a hormone and a neurotransmitter.As a stress hormone, norepinephrine affects parts of the brain where attention and responding actions are controlled....
. Epinephrine
Epinephrine

Epinephrine is a hormone and neurotransmitter.Epinephrine increases the "fight or flight" response of the Sympathetic nervous system of the autonomic nervous system....
 infusions are less vasoconstrictive than norepinephrine as they primarily stimulate beta receptor more than alpha receptors, but the effect remains dose dependent.

Phentolamine also has diagnostic and therapeutic roles in complex regional pain syndrome
Complex regional pain syndrome

Complex Regional Pain Syndrome is a chronic progressive disease characterized by severe pain, swelling and changes in the skin. The International Association for the Study of Pain has divided CRPS into two types based on the presence of nerve lesion following the injury....
 (reflex sympathetic dystrophy).