Respiratory Drugs and Medications Q 14
Nurse Rita is giving instructions to her client who is taking antihistamine. Which of the following nurse teachings is appropriate for the client?
A. Avoid ingesting alcohol
B. Be aware that you may need to take a decongestant
C. Be aware that you may have increased saliva
D. Expect relief in 24 hours
Correct Answer: A. Avoid ingesting alcohol
Because alcohol and antihistamines have sedating properties, concurrent administration of these drugs should be avoided. Antihistamines are a pharmaceutical class of drugs that act to treat histamine-mediated conditions. There are two main classes of histamine receptors: H-1 receptors and H-2 receptors. Antihistamine drugs that bind to H-1 receptors are generally used to treat allergies and allergic rhinitis. Drugs that bind to H-2 receptors treat upper gastrointestinal conditions that are caused by excessive stomach acid.
Option B: Antihistamines and decongestants are often given together. Histamine (an endogenous chemical messenger) induces an increased level of vascular permeability, which leads to fluid moving from capillaries into the surrounding tissues. The overall outcome of this is increased swelling and dilation of vessels. Antihistamines stop this effect by acting as antagonists at the H-1 receptors. The clinical benefit is a reduction in allergy symptoms and any related symptoms.
Option C: Dry mouth is a common side effect, not increased salivation. H-1 receptor antihistamines have anticholinergic properties, which are adverse effect-inducing; this principally occurs from the first generation category of antihistamines only. As a whole, they are sedating but may cause insomnia in some users. Due to their anticholinergic properties, dry mouth is a relatively common adverse effect.
Option D: Not all antihistamines last 24 hours. The duration of the pharmacological action of first-generation antihistamines is about 4 to 6 hours. In contrast, second-generation antihistamines work for 12 to 24 hours. They are both metabolized by the liver using the P450 cytochrome system.