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.
Simvastatin
Common side effects (>1% incidence) may include indigestion and eczema. Rare side effects include joint pain, memory loss, and muscle cramps. Cholestatic hepatitis, hepatic cirrhosis, rhabdomyolysis (destruction of muscles and blockade of renal system), and myositis have been reported in patients receiving the drug chronically. Serious allergic reactions to simvastatin are rare. If the following signs of a serious allergic reaction occur, seek medical attention immediately: rash, hoarsness itching/swelling, dizziness, or difficulty swallowing/breathing.