From the FDA Drug Label
For preoperative reduction of elevated blood pressure, 5 mg of phentolamine mesylate (1 mg for children) is injected intravenously or intramuscularly 1 or 2 hours before surgery, and repeated if necessary During surgery, phentolamine mesylate (5 mg for adults, 1 mg for children) is administered intravenously as indicated, to help prevent or control paroxysms of hypertension, tachycardia, respiratory depression, convulsions, or other effects of epinephrine intoxication
- Phentolamine is used to prevent or control effects of epinephrine intoxication, which can be considered as an antidote to adrenalin (also known as epinephrine) 1.
- The typical dose for adults is 5 mg of phentolamine mesylate administered intravenously.
From the Research
The antidote for adrenaline (epinephrine) overdose is typically a beta-blocker medication, with propranolol being the most commonly used option, as it can effectively counteract the effects of adrenaline on the body, such as increased heart rate and blood pressure elevation, as noted in studies like 2 and 3. When considering the treatment of adrenaline overdose, it's crucial to prioritize the most recent and highest quality evidence available. In this context, the use of beta-blockers, particularly propranolol, is supported by various studies, including those that highlight the pharmacologic differences between beta blockers 2 and their application in clinical settings 3. The administration of propranolol for severe adrenaline overdose can be done intravenously at a rate of 1 mg per minute, up to 1-3 mg, with careful monitoring of vital signs, as indicated in general medical practice. For less severe cases, oral propranolol at 20-40 mg may be used. Other beta-blockers like metoprolol or atenolol can serve as alternatives, but the choice of medication should be guided by the most current clinical guidelines and the patient's specific condition, considering factors such as the presence of asthma, which may necessitate caution due to the potential for beta-blockers to trigger bronchospasm, as discussed in 2. Treatment should always occur in a medical setting with continuous cardiac monitoring, as these medications can cause bradycardia and hypotension. Supportive care, including oxygen, IV fluids, and management of symptoms, is essential alongside the antidote. The mechanism by which beta-blockers counteract adrenaline effects involves blocking the beta-adrenergic receptors, thereby mitigating symptoms like increased heart rate, blood pressure elevation, and tremors, as explained in the context of adrenaline's action in the body 4. Given the potential for adverse effects and the importance of monitoring, it's critical to approach the treatment of adrenaline overdose with caution, prioritizing the patient's safety and adjusting the treatment plan as necessary based on their response to the antidote and any supportive care measures, aligning with general principles of managing poisoned patients 5.