Preparation for Child Psych PRITE and Boards
Revision as of 15:08, 25 April 2015 by Eugene Grudnikoff MD (Talk | contribs)
Introduction
All medications designated as antihistamines are strong antagonists or inverse agonist at the peripheral and central histamine receptors.
- Blockade or the inverse agonism of the peripheral H-1 receptor alleviates allergy symtpoms.
- Blockade or inverse agonism of the central H-1 receptor increases sedation.
- Second-generation antihistamines do not cross the blood-brain barrier, and thus are less sedating.
Diphenhydramine (Benadryl)
- Benadryl is a first-generation antihistamine; in addition to blocking H-1 receptors, it is a potent anti-cholinergic drug and therefore can be used to mitigate extrapyramidal effects of antipsychotics, and has a role in treatment of Parkinson's disease. As noted above, it crosses the blood-brain barrier, and thus quite sedating
- Its use is generally avoided in the elderly due to significant sedation (risk of falls) and potential for anti-cholinergic toxicity (dry mouth, tachycardia, urinary retention, and delirium)
- Benadryl is frequently used in inpatient child psychiatry as a PRN medication for it's sedating properties.
- Benadryl is generally safe in pregnancy (Category B), but is excreted in breast milk.
- It can prolong QTc in large doses or in combination with other QTc-prolonging medications.
==Hydroxyzine (Vistaril, Atarax)