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.
NS5B inhibitor
Comparing virological response of NS5B inhibitors to previous therapy of chronic hepatitis C with the combination of interferon and ribavirin, it was possible to observe a significant difference in efficacy and safety. The efficacy rate of interferon plus ribavirin varied within 44-46% while it increases up to 90% by direct acting antivirals such as NS5B inhibitors/ Data on the frequency of side effects may vary between researches for both drug categories. Nevertheless, there is a significant difference between the safety profiles of NS5B inhibitors, particularly sofosbuvir and the combination of interferon and ribavirin. Comparing interferon containing therapies, sofosbuvir does not cause neutropenia, thrombocytopenia, or any other serious adverse effects. Common side effects associated with sofosbuvir are headache, tiredness, insomnia, dizziness, itching, infections of upper respiratory tract, rashes, back pain, anemia, and lymphopenia. With the advent of direct acting antivirals, the duration of the hepatitis treatment has also been impressively reduced. Severity of adverse effects is strongly associated with duration of therapy and the dose used for hepatitis C treatment. Therefore, direct actung antivirals have become the initial treatment ised for most patients with chronic hepatitis C.