Browsing Pathways

Hydroxyethylpromethazine is a first-generation phenothiazine H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.

Mirtazapine is a tetracyclic H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.

Flunarizine is a first-generation H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.

Epinastine is a second-generation tetracyclic H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.

Phenindione is a medication that is used as an anticoagulant. Anticoagulants are drugs that prevent the blood from coagulating and creating blood clots. It is used to treat a variety of conditions, including cerebral and pulmonary embolisms, as well as cardiomyopathy. Phenindione works by thinning the blood, which is done through the antagonization of vitamin K. This antagonization is needed to create the factors that cause clotting in the liver. Phenindione resembles warfarin action-wise, but warfarin is preferentially used as there have been more instances in hypersensitivity in phenindione patients.

Reteplase is an enzyme that is part of the thrombolytics drug class, used to dissolve or break down blood clots. Reteplase activates plasminogen. Then zooming in even further to the endoplasmic reticulum within the liver, vitamin K1 2,3-epoxide uses vitamin K epoxide reductase complex subunit 1 to become reduced vitamin K (phylloquinone), and then back to vitamin K1 2,3-epoxide continually through vitamin K-dependent gamma-carboxylase. This enzyme also catalyzes precursors of prothrombin and coagulation factors VII, IX and X to prothrombin, and coagulation factors VII, IX and X. From there, these precursors and factors leave the liver cell and enter into the blood capillary bed. Once there, prothrombin is catalyzed into the protein complex prothrombinase complex which is made up of coagulation factor Xa/coagulation factor Va (platelet factor 3). These factors are joined by coagulation factor V. Through the two factors coagulation factor Xa and coagulation factor Va, thrombin is produced, which then uses fibrinogen alpha, beta, and gamma chains to create fibrin (loose). This is then turned into coagulation factor XIIIa, which is activated through coagulation factor XIII A and B chains. From here, fibrin (mesh) is produced which interacts with endothelial cells to cause coagulation. Plasmin is then created from fibrin (mesh), then joined by tissue-type plasminogen activator (reteplase) through plasminogen, and creates fibrin degradation products. These are enzymes that stay in your blood after your body has dissolved a blood clot. Coming back to the factors transported from the liver, coagulation factor X is catalyzed into a group of enzymes called the tenase complex: coagulation factor IX and coagulation factor VIIIa (platelet factor 3). This protein complex is also contributed to by coagulation factor VIII, which through prothrombin is catalyzed into coagulation factor VIIIa. From there, this protein complex is catalyzed into prothrombinase complex, the group of proteins mentioned above, contributing to the above process ending in fibrin degradation products. Another enzyme transported from the liver is coagulation factor IX which becomes coagulation factor IXa, part of the tense complex, through coagulation factor XIa. Coagulation factor XIa is produced through coagulation factor XIIa which converts coagulation XI to become coagulation factor XIa. Coagulation factor XIIa is introduced through chain of activation starting in the endothelial cell with collagen alpha-1 (I) chain, which paired with coagulation factor XII activates coagulation factor XIIa. It is also activated through plasma prekallikrein and coagulation factor XIIa which activate plasma kallikrein, which then pairs with coagulation factor XII simultaneously with the previous collagen chain pairing to activate coagulation XIIa. Lastly, the previously transported coagulation factor VII and tissue factor coming from a vascular injury work together to activate tissue factor: coagulation factor VIIa. This enzyme helps coagulation factor X catalyze into coagulation factor Xa, to contribute to the prothrombinase complex and complete the pathway.

Phenprocoumon is an anticoagulant that inhibits the liver enzyme vitamin K reductase. This leads to the depletion of the reduced form of vitamin K (vitamin KH2). As vitamin K is a cofactor for the gamma-carboxylation and subsequent activation of the vitamin K-dependent coagulation factors (II, VII, IX, and X), this ultimately results in reduced cleavage of fibrinogen into fibrin and decreased coagulability of the blood.

Alteplase is the generic version of the drugs Activase and Actilyse. It is a thrombolytic drug prescribed to treat acute myocardial infarctions and other blood clotting conditions. Alteplase if often used to treat ischaemic stroke within hours of onset. The drug acts by breaking up blood clots. Alteplase binds fibrin in the blood clot to converts plasminogen to plasmin. Plasmin is a proteolytic enzyme that causing the degradation of fibrin. A side effect of the drug is bleeding, angioedema, allergic reactions and fever.

2-Hydroxyglutarate is a compound formed from isocitric acid, a component of the TCA cycle. Isocitric acid becomes dehydrogenated by isocitrate dehydrogenase using NADP as a cofactor, and forming oxoglutaric acid. Oxoglutaric acid then forms 2-hydroxyglutarate in a reaction catalyzed by a mutant isocitrate dehydrogenase 2 enzyme, which also uses NADP as a cofactor. Normally, the isocitrate dehydrogenase 2 enzyme, encoded by the IDH2 gene, is responsible for the formation of 2-oxoglutaric acid from isocitrate. However, some gain-of-functions mutations to the IDH2 gene allow the enzyme to produce 2-hydroxyglutarate instead. This functionality is associated with several types of cancer, including glioma and acute myeloid leukemia. This is due to the buildup of 2-hydroxyglutarate, which inhibits several enzymes which rely on 2-oxoglutaric acid, such as methylcytosine dioxygenase and lysine-specific demethylase 2A. Both of these enzymes use 2-oxoglutarate to demethylate DNA, and when repressed, allow DNA to become hypermethylated. This in turn changes which genes are normally expressed, as methylation is used to suppress genes, and can lead to the expression of oncogenes or the repression of tumor-suppressing genes. This is the effect responsible for 2-hydroxyglutarate in cancer and other diseases.

Famotidine (also known as Pepcid) can bind and inhibit histamine H2 receptor on parietal cell's basolateral membrane. Binding of famotidine can effectively inhibit the histamine effects, which lead to reduced nocturnal gastric acid and basal secretion; it can also decrease gastric volume, gastric acid and acidity.