Browsing Pathways

Oxaprozin (also named Daypro, Dayrun) is a nonsteroidal anti-inflammatory drug (NSAID). It can be used to relieve pain (analgesic) and reduce fever (antipyretic). Oxaprozin is also a type of ophthalmic anti-inflammatory medicines which may be used to help prevent eye constrict for pupil during surgery. Oxaprozin can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Since prostaglandin is the messenger molecules in the process of inflammation; hence, inhibition of prostaglandin synthesis can reduce the pain and inflammation.

Nabumetone (also named Relafen and Relifex) is a nonsteroidal anti-inflammatory drug (NSAID). It can be used to relieve pain (analgesic) and reduce fever (antipyretic). Nabumetone can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Since prostaglandin is the messenger molecules in the process of inflammation; hence, inhibition of prostaglandin synthesis can reduce the pain, fever and inflammation.

Furosemide (also named Lasix) is a medication that can be used for high blood pressure and fluid build-up which caused by heart failure, liver scarring, or kidney disease. Furosemide can bind and inhibit sodium-potassium-chloride cotransporter (NKCC2/SLC22A1) to prevent the water reabsorption in nephron. Inhibition of sodium-potassium-chloride cotransporter can prevent transportation of sodium from lumen to basolateral interstitium, which lead to more hypertonic in lumen and less hypertonic in basolateral interstitium that will allow water reabsorption through nephron.

Valdecoxib, a selective prostaglandin G/H synthase 2 (better known as cyclooxygenase-2 or COX-2) inhibitor, is classified as a nonsteroidal anti-inflammatory drug (NSAID). Valdecoxib was used for its anti-inflammatory, analgesic, and antipyretic effects in the management of osteoarthritis and for the treatment of dysmenorrhea or acute pain. Unlike celecoxib, valdecoxib lacks a sulfonamide chain and does not require CYP450 enzymes for metabolism. Both COX-1 and COX-2 catalyze the conversion of arachidonic acid to prostaglandin G2 (PGG2) and PGG2 to prostaglandin H2 (PGH2). PGH2 is the precursor of a number of prostaglandins, including prostaglandin E2 (PGE2), prostaglandin I2 (PGI2) and thomboxane A2 (TxA2). Valdecoxib selectively inhibits the cyclooxygenase-2 (COX-2) enzyme, a key enzyme in the production of PGE2. PGE2 is a potent mediator of pain, inflammation and fever. The first part of this figure depicts the anti-inflammatory, analgesic and antipyretic pathway of valdecoxib. The latter portion of this figure depicts valdecoxib’s potential involvement in platelet aggregation. Prostaglandin synthesis varies across different tissue types. Platelets, anuclear cells derived from fragmentation from megakaryocytes, contain COX-1, but not COX-2. COX-1 activity in platelets is required for thromboxane A2 (TxA2)-mediated platelet aggregation. Platelet activation and coagulation do not normally occur in intact blood vessels. After blood vessel injury, platelets adhere to the subendothelial collagen at the site of injury. Activation of collagen receptors initiates phospholipase C (PLC)-mediated signaling cascades resulting in the release of intracellular calcium from the dense tubula system. The increase in intracellular calcium activates kinases required for morphological change, transition to procoagulant surface, secretion of granular contents, activation of glycoproteins, and the activation of phospholipase A2 (PLA2). Activation of PLA2 results in the liberation of arachidonic acid, a precursor to prostaglandin synthesis, from membrane phospholipids. The accumulation of TxA2, ADP and thrombin mediates further platelet recruitment and signal amplification. TxA2 and ADP stimulate their respective G-protein coupled receptors, thomboxane A2 receptor and P2Y purinoreceptor 12, and inhibit the production of cAMP via adenylate cyclase inhibition. This counteracts the adenylate cyclase stimulatory effects of the platelet aggregation inhibitor, PGI2, produced by neighbouring endothelial cells. Platelet adhesion, cytoskeletal remodeling, granular secretion and signal amplification are independent processes that lead to the activation of the fibrinogen receptor. Fibrinogen receptor activation exposes fibrinogen binding sites and allows platelet cross-linking and aggregation to occur. Neighbouring endothelial cells found in blood vessels express both COX-1 and COX-2. COX-2 in endothelial cells mediates the synthesis of PGI2, an effective platelet aggregation inhibitor and vasodilator, while COX-1 mediates vasoconstriction and stimulates platelet aggregation. PGI2 produced by endothelial cells encounters platelets in the blood stream and binds to the G-protein coupled prostacyclin receptor. This causes G-protein mediated activation of adenylate cyclase, which catalyzes the conversion of adenosine triphosphate (ATP) to cyclic AMP (cAMP). Four cAMP molecules then bind to the regulatory subunits of the inactive cAMP-dependent protein kinase holoenzyme causing dissociation of the regulatory subunits and leaving two active catalytic subunit monomers. The active subunits of cAMP-dependent protein kinase catalyze the phosphorylation of a number of proteins. Phosphorylation of inositol 1,4,5-trisphosphate receptor type 1 on the endoplasmic reticulum (ER) inhibits the release of calcium from the ER. This in turn inhibits the calcium-dependent events, including PLA2 activation, involved in platelet activation and aggregation. Inhibition of PLA2 decreases intracellular TxA2 and inhibits the platelet aggregation pathway. cAMP-dependent kinase also phosphorylates the actin-associated protein, vasodilator-stimulated phosphoprotein. Phosphorylation inhibits protein activity, which includes cytoskeleton reorganization and platelet activation. Valdexocib preferentially inhibits COX-2 with little activity against COX-1. COX-2 inhibition in endothelial cells decreases the production of PGI2 and the ability of these cells to inhibit platelet aggregation and stimulate vasodilation. These effects are thought to be responsible for the rare, but severe, adverse cardiovascular effects observed with rofecoxib, a COX-2 inhibitor which was subsequently been withdrawn from the market. Valdexocib was withdrawn from the Canadian, U.S. and E.U. markets in 2005 due to concerns of possible increased risk of heart attack and stroke.

Ibandronate (also named ibandronate sodium) is a type of medication that used to treat numbers of bone diseases because of its affinity for hydroxyapatite. Ibandronate targets farnesyl pyrophosphate (FPP) synthase by inhibiting the function of this enzyme in the mevalonate pathway, which prevent the biosynthesis of Geranyl-PP and farnesyl pyrophosphate. Geranyl-PP and farnesyl pyrophosphate are important for geranylgeranylation and farnesylation of GTPase signalling proteins. Lack of Geranyl-PP and farnesyl pyrophosphate will result in decreased rate of bond resorption and turnover as well as block the osteoclast activity, which lead to an increasing mass gain in bone (i.e. net gain in bone mass).

Torsemide, also known as torasemide is a pharmacologically-active small molecule that belongs to the drug class of loop diuretics. It is commonly used to manage hypertension and edema in cases of congestive heart failure as it acts as a diuretic by blocking sodium transporters NKCC2 on the thick ascending limb of the Loop of Henle in the renal tissues. Specifically it acts on solute carrier family 12 member 1. This prevents the reuptake of sodium into the Loop of Henle which consequentially reduces the uptake of water and serves to both increase water loss and reduce blood pressure. Torsemide appears to reduce blood pressure beyond its action in reducing salt uptake in the Loop of Henle; it also seems to be involved in reducing vasoconstriction by blocking the action of angiotensin II.

Fluvastatin inhibits cholesterol synthesis via the mevalonate pathway by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. HMG-CoA reductase is the enzyme responsible for the conversion of HMG-CoA to mevalonic acid, the rate-limiting step of cholesterol synthesis by this pathway. Fluvastatin bears a chemical resemblance to the reduced HMG-CoA reaction intermediate that is formed during catalysis. Fluvastatin was the first synthetically-prepared HMG-CoA reductase inhibitor. Although similar to lovastatin, simvastatin, and pravastatin, it has a shorter half-life, no active metabolites, extensive protein binding, and minimal CSF penetration. Cholesterol biosynthesis accounts for approximately 80% of cholesterol in the body; thus, inhibiting this process can significantly lower cholesterol levels.

Naproxen (also named Aleve and Naprosyn) is a nonsteroidal anti-inflammatory drug (NSAID). It can be used to relieve pain (analgesic) and reduce fever (antipyretic). Naproxen is also a type of ophthalmic anti-inflammatory medicines. Naproxen can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Since prostaglandin is the messenger molecules in the process of inflammation; hence, inhibition of prostaglandin synthesis can reduce the pain and inflammation.

Trichlormethiazide is a pharmacologically-active small molecule that belongs to a class of drugs called thiazides. Thiazides and thiazide-like drugs are diuretics commonly employed to control hypertension. Trichloromethiazide acts by inhibiting chloride and potentially sodium reabsorption in the ascending loop of Henle, specifically at solute carrier family 12 member 3. This action results in increased fluid loss which ultimately reduces blood volume and pressure. Trichlormethiazide also acts to inhibit sodium uptake and increase potassium excretion which also serves to increase fluid loss. The long-term antihypertensive effects of thiazides and thiazide-like drugs such as trichlormethiazide are not well-characterized but may involve its action on carbonic anhydrases.

Chlorthalidone (also known as chlorthalidone or phthalamudine) is an organic compound that used for diuretic. It can inhibit the solute carrier family 12 member 3 (also known as sodium-chloride symporter) in the nephron to prevent water reabsorption. Solute carrier family 12 member 3 is also used for sodium reabsorption that count for 5% of total amount. Solute carrier family 12 member 3 transports chloride and sodium from lumen to epithelial cell, and sodium/potassium ATPases facilitate the export of sodium to basolateral interstitium to provide sodium gradient that will increase the osmolarity in interstitium, which lead to establishment of osmotic gradient for water reabsorption.