Histamine is referred to as common allergic reactions and symptoms. Most of them are compared to histamine intolerance. Some common responses involved with this intolerance may vary but include headaches or migraines, nasal congestion or sinus problems, fatigue, hives, digestive problems, irregular menstrual cycle, nausea, and vomiting. Histamine is derived from a natural amino acid, S-histidine, through the histidine decarboxylase/ aromatic decarboxylase catalysis. Histamine is the compound that the mast cell generates for the immune response. Histamine promotes gastrointestinal secretion and induces capillary dilation, bronchial smooth muscle constriction, and reduced blood pressure. Antihistamines are medicinal products to treat allergic rhinitis and allergies. This includes the in vitro animal model and in-vivo tissue preparation antihistaminic activity. Animal models are significant instruments for understanding the pathological process of human illnesses in experimental medical science. Medicines associated with antihistamine include antiallergy, antivertigo, antimigraine, sedatives, antiemetic, etc. Elderly people are much more likely than youthful people to develop sleepiness from the use of antihistamines. The most common drugs used are cetirizine, levocetirizine, chlorpheniramine, diphenhydramine, loratadine, cimetidine, and fexofenadine. Animal models include histamine-induced bronchoconstriction, passive paw anaphylaxis, milk-induced leukocytosis and eosinophilia, clonidine, and haloperidol-induced catalepsy. While tissue models include isolated goat, and guinea-pig trachea chain preparation, as well as an isolated guinea pig, rat, mice ileum tissue preparation, and the dose-response curve of histamine, were plotted. The focus of the study had been on herbal plants and medicinal products, as they can effectively boost a variety of circumstances without significant adverse side effects. We can assess antihistaminic activity by using plant extracts or any synthetic drug.
ANTIHISTAMINIC ACTIVITY MODELS
