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Hallucinogens and Phencyclidine
Published in Frank Lynn Iber, Alcohol and Drug Abuse as Encountered in Office Practice, 2020
Toxic reactions are common and usually occur in an experienced user who has taken an unusually high or rapidly repeated doses of drug. Within 30 min a very exaggerated adrenergic response, with marked anxiety, prominent pounding of the heart, and anxiety, occurs. The pupils are widely dilated, the blood pressure and pulse are elevated, and there may be fever. In extreme circumstances vascular collapse and convulsions may occur. The psyche demonstrates hallucinations and loss of reality, and there is marked fear. Distortion and intensification of sensory perception is usually present, such as hearing color or feeling sounds. Depersonalization and confusion are often prominent. The symptoms disappear completely in 12 to 24 h. If hyperthermia is prominent, an ice bath or a cooling blanket may be needed. If the blood pressure is alarmingly elevated, phentolamine i.v. may be indicated. Convulsions are usually managed with phenytoin or diazepam. Anxiety is usually allayed by supporting the patient, and only rarely is a drug such as diazepam, 10 to 30 mg orally, repeated 10 to 15 mg each 2 h, required. With LSD the reaction is over in 24 h. If it persists, other drugs such as STP or PCP should be considered.
Erectile dysfunction and Peyronie’s disease
Published in J Kellogg Parsons, E James Wright, The Brady Urology Manual, 2019
Trinity J Bivalacqua, Mohamad E Allaf
Phentolamine: Competitive alpha-1 and alpha-2 adrenergic antagonist that reduces penile vascular tone and contributes to corporal smooth muscle relaxationDose: 1 mgAs a single agent it is minimally efficacious but is commonly used in combination to potentiate papaverine and/or PGE1
Evaluation of Autonomic Failure
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
B) Blood pressure and heart rate are determined with the patient in resting state. An intravenous line is placed and after 30 minutes a bolus dose of 0.5 mg of phentolamine is given as a test dose. If the patient tolerates this without significant response in the first minute following administration, a 4.5 mg bolus injection is given. Blood pressure and heart rate are determined immediately afterwards and at 1 minute intervals for 5 minutes.
A review on pharmacological options for the treatment of erectile dysfunction: state of the art and new strategies
Published in Expert Opinion on Pharmacotherapy, 2023
Mattia Longoni, Alessandro Bertini, Nicolò Schifano, Emanuele Zaffuto, Paolo Maggio, Rossi Piercarlo, Sara Baldini, Giulio Carcano, Gabriele Antonini, Andrea Salonia, Francesco Montorsi, Federico Dehò, Paolo Capogrosso
Phentolamine is a nonselective α-adrenergic antagonist that decreases arterial resistance and promotes vasodilatation by inhibiting smooth muscle cell contraction [75]. The commercial preparation of Bimix, approved for clinical use in some European countries, contains papaverine hydrochloride (15 mg/mL) and phentolamine mesylate (0.5 mg/mL) in 2-mL vials [61]. The combination of these two drugs has shown the same efficacy and equal rate of prolonged erection compared to PGE1 30 μg alone, whereas it caused significantly less injection pain (15% vs 35%, p < 0.05) [76]. The addition of alprostadil (Trimix) provides the highest efficacy rates, reaching up to 92% [77,78]. This three-drug combination has similar adverse effects as alprostadil monotherapy, although fibrosis is more common when a higher dose of papaverine is used (5–10%) [77]. Noteworthy, hypotension could potentially occur with higher concentrations of the compounds [53]. In a randomized clinical trial, the combination of papaverine 17.64 mg + phentolamine 0.58 mg + PGE1 5.8 μg had a twofold efficacy rate compared to PGE1 40 μg monotherapy (50% vs 22%), with very low pain (12.5% vs 22%) due to the reduced dose of alprostadil being used [79]. Therefore, Trimix could be a suitable option for patients who underwent radical pelvic surgery as pain or tenderness after PGE1 is accentuated by an underlying cavernous nerve injury [53,63]. Unfortunately, no commercially marketed preparation for Trimix is available, due to the low stability of the combined agents.
Management of a patient with unintended intravenous dihydroergotamine infusion extravasation causing brachial artery vasospasm
Published in Baylor University Medical Center Proceedings, 2023
Extravasation injuries occur in 0.1% to 6% of adult patients and up to 11% of pediatric patients.9,10 The physicochemical properties of an infiltrated substance will typically determine the propensity for tissue damage after infiltration. Nitropaste, nitroprusside infusions, and intradermal phentolamine injections were initially attempted in our patient with minimal results. Nitropaste has been well documented in effectively treating cerebral vasospasms and vasospastic conditions such as Raynaud’s phenomenon11,12 via relaxation of the smooth muscles within the arterioles and venules.13 Nitroprusside infusions can be helpful in relieving cerebral vasospasms and have been reported in treating systemic ergotism induced limb ischemia with some efficacy.7,8 Phentolamine is a competitive nonselective alpha-adrenergic receptor antagonist and is the drug of choice in treating sympathomimetic vasopressor extravasation, such as epinephrine and norepinephrine.14,15 There is currently minimal literature on the effectiveness of intradermal phentolamine in treating extravasation of other medications with vasopressor properties, such as DHE. This patient ultimately required invasive intervention in the operating room to manage the iatrogenic vasoconstriction of the brachial artery.
Impact of chronic medications in the perioperative period: mechanisms of action and adverse drug effects (Part I)
Published in Postgraduate Medicine, 2021
Ofelia Loani Elvir-Lazo, Paul F White, Hillenn Cruz Eng, Firuz Yumul, Raissa Chua, Roya Yumul
Adverse effects associated with α2 agonists include hypotension, bradycardia, dry mouth, and sedation. At high doses, respiratory depression may occur. Clonidine withdrawal has also been reported to produce rebound hypertension and elevated plasma catecholamine concentrations. This side effect can be reversed with IV phentolamine. Other clonidine withdrawal symptoms include headache, agitation, nervousness, and rarely hypertensive encephalopathy, cerebrovascular accident, and even death [12]. Epidural clonidine can cause severe hypotension, especially in women and those of low body weight, and it is not recommended for perioperative, obstetrical, or postpartum pain due to concerns regarding hemodynamic instability [13].