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Agostic interactions are best demonstrated by crystallography. Neutron diffraction data have shown that C−H and M┄H bond distances are 5-20% longer than expected for isolated metal hydride and hydrocarbons. The distance between the metal and the hydrogen is typically 1.8–2.3 Å, and the M
The proton pump is the terminal stage in gastric acid secretion, being directly responsible for secreting H + ions into the gastric lumen, making it an ideal target for inhibiting acid secretion. [ citation needed ] Because the H,K-ATPase is the final step of acid secretion, an inhibitor of this enzyme is more effective than receptor ...
A derivative of timoprazole, omeprazole, was discovered in 1979, and was the first of a new class of drug that control acid secretion in the stomach, a proton pump inhibitor (PPI). [ 11 ] [ 12 ] Addition of 5-methoxy-substitution to the benzimidazole moiety of omeprazole was also made and gave the compound much more stability at neutral pH. [ 6 ]
These drugs are among the most widely sold drugs in the world, and are generally considered effective. [3] When these medications are used long term, the lowest effective dose should be taken. [4] They may also be taken only when symptoms occur in those with frequent problems. [5] Proton-pump inhibitors are named using the suffix "-prazole".
An example of a proton pump that is not electrogenic, is the proton/potassium pump of the gastric mucosa which catalyzes a balanced exchange of protons and potassium ions. [citation needed] The combined transmembrane gradient of protons and charges created by proton pumps is called an electrochemical gradient.
All proton pump inhibitors except for rabeprazole and pantoprazole are metabolized by the hepatic CYP450 enzyme and therefore, may interact with the metabolism of clopidogrel. Omeprazole is considered to have higher potential for drug-drug interaction than other protein pump inhibitors because it is a CYP2C19 inhibitor. [17]
Due to irreversible binding of the pumps, new pumps have to be made before acid production can be resumed. [9] The drug's plasma half-life is about two hours. [27] After administration, the time for the drug to reach peak plasma concentrations is 2 to 3 hours. [17] The percentage of the drug that is protein bound is 98%. [17]
The hydride reacts with the weak Bronsted acid releasing H 2. Hydrides such as calcium hydride are used as desiccants, i.e. drying agents, to remove trace water from organic solvents. The hydride reacts with water forming hydrogen and hydroxide salt. The dry solvent can then be distilled or vacuum transferred from the "solvent pot".