Phentolamine / Regitine Flashcards
Drug Class (Pharmacologic and Therapeutic)
Pharm: Non-selective, competitive alpha-adrenergic receptor blocker
Therapeutic: antihypertensive drug for patients with pheochromocytoma
Pharmacodynamics
Blocks alpha 1 and alpha 2 adrenergic receptors at presynaptic and postsynaptic alpha receptors, decreasing preload and afterload
Pharmacokinetics
Only comes in IV formulation, so F=100%; plasma half-life about 20 min after IV dose
Toxicity
Excessive hypotension with syncope, especially orthostatic, especially in patients on diuretics; allergic reactions; decreased libido
Interactions
Additive effects with most other antihypertensives, especially diuretics
Special Considerations
Rule out carcinoma of prostate before beginning treatment, do not crush or chew tablets, as that will speed up absorption; can also be used to treat spasm of ureter in patients with kidney stones
Indications and dose / route
Aid in Dx of pheo; treatment of intra-op HTN during pheo removal surgery; prevention of dermal sloughing after extravasation of NE infusion; hypertensive crisis from sympathomimetic amines (discuss tyramine-MAO interaction) ; Dose 5 mg IV, then titrate, repeat as needed
Monitor BP!!!
BP!!!