Final answer:
First-generation H1 blockers work by binding to histamine H1 receptors to treat allergic reactions. Potential toxicities include drowsiness and anticholinergic effects.
Step-by-step explanation:
First-generation H1 blockers work by binding to histamine H1 receptors in mast cells, smooth muscle, and endothelium in the body as well as in the tuberomammillary nucleus in the brain. They are used to treat allergic reactions in the nose, such as itching, runny nose, and sneezing. Additionally, they can be used to treat insomnia, motion sickness, or vertigo caused by inner ear problems.
Some potential toxicities of first-generation H1 blockers include drowsiness, dry mouth, blurred vision, and urinary retention. These side effects are due to the drugs' ability to cross the blood-brain barrier and bind to H1 receptors in the central nervous system. They can also have anticholinergic effects, leading to constipation and increased heart rate.
Examples of first-generation H1 blockers include diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton).