Antihistamine
The vast majority of marketed H-antihistamines are receptor antagonists and only a minority of marketed compounds are inverse agonists at the receptor. Clinically, H-antihistamines are used to treat allergic reactions and mast cell-related disorders. Sedation is a common side effect of H-antihistamines that readily cross the blood–brain barrier; some of these drugs, such as diphenhydramine and doxylamine, are therefore used to treat insomnia. H-antihistamines can also reduce inflammation, since the expression of NF-κB, the transcription factor the regulates inflammatory processes, is promoted by both the receptor's constitutive activity and agonist (i.e., histamine) binding at the H receptor.
Side effects of bicalutamide
Combination of bicalutamide with medical (i.e., a analogue) or surgical castration modifies the side effect profile of bicalutamide. Some of its side effects, including breast pain/tenderness and gynecomastia, are far less likely to occur when the drug is combined with a analogue, while certain other side effects, including hot flashes, depression, fatigue, and sexual dysfunction, occur much more frequently in combination with a analogue. It is thought that this is due to the suppression of estrogen levels (in addition to androgen levels) by analogues, as estrogens may compensate for various negative central effects of androgen deprivation. If bicalutamide is combined with a analogue or surgical castration, the elevation of androgen and estrogen levels in men caused by bicalutamide will be prevented and the side effects of excessive estrogens, namely gynecomastia, will be reduced. However, due to the loss of estrogen, bone loss will accelerate and the risk of osteoporosis developing with long-term therapy will increase.