Omeprazole
It is a proton pump inhibitor used in the treatment of dyspepsia, peptic ulcer disease (PUD), gastroesophageal reflux disease (GORD/GERD), laryngopharyngeal reflux (LPR) and Zollinger-Ellison syndrome. Omeprazole was first marketed in the U.S. in 1989 by AstraZeneca under the brand names Losec and Prilosec. Prilosec contains the active ingredient omeprazole and Prilosec OTC contains the active ingredient omeprazole magnesium. It is now also available from generic manufacturers under various brand names. Omeprazole is one of the most widely prescribed drugs internationally and is available over the counter in some countries. In pharmacology, Omeprazole is a racemate. It contains a tricoordinated sulfur in a pyramidal structure and therefore can exist in equal amounts of both the S and R enantiomers. In the acidic conditions of the stomach, both are converted to achiral products, which reacts with a cysteine group in H+/K+ ATPase, thereby inhibiting the ability of the parietal cells to produce gastric acid.
Usages and side effects
According to AstraZeneca, omeprazole undergoes a chiral shift in vivo, which converts the inactive R-enantiomer to the active S-enantiomer doubling the concentration of the active form. This chiral shift is accomplished by the CYP2C19 isozyme of cytochrome P450, which is not found equally in all human populations. Those who do not metabolize the drug effectively are called "poor metabolizers." The approximate proportion of the poor metabolizer phenotype in different populations is as follows Caucasians (10%), Asian (20%) and South Pacific Islands (70%). Furhter, omeprazole can also be used in the treatment of rare forms of herpes simplex virus 1 and 2 (HSV-1 and HSV-2) as noted in the case of Garner, R. 2008. Omeprazole is combined with the antibiotics clarithromycin and amoxicillin (or metronidazole in penicillin-hypersensitive patients) in the 7-14 day eradication triple therapy for Helicobacter pylori. Infection by H. pylori is the causative factor in the majority of peptic and duodenal ulcers. Omeprazole is available as cheap cialis and capsules (containing omeprazole or omeprazole magnesium) in strengths of 10 mg, 20 mg, 40 mg and in some markets 80 mg; and as a powder (omeprazole sodium) for intravenous injection. Most oral omeprazole preparations are enteric-coated, due to the rapid degradation of the drug in the acidic conditions of the stomach. This is most commonly achieved by formulating enteric-coated granules within capsules, enteric-coated tablets, and the multiple-unit pellet system (MUPS). It is also available for use in injectable form (I.V.) in Europe, but not in the U.S. The injection pack is a combination pack consisting of a vial and a separate ampule of reconstituting solution. Each 10 ml clear glass vial contains a white to off-white lyophilised powder consisting of omeprazole sodium 42.6 mg equivalent to 40 mg of omeprazole. Some of the most frequent side effects of omeprazole (experienced by over 1% of those taking the drug) are headache, diarrhea, abdominal pain, nausea, dizziness, trouble awakening and sleep deprivation, although in clinical trials the incidence of these effects with omeprazole was mostly comparable to that found with placebo. Proton pump inhibitors may be associated with a greater risk of hip fractures and Clostridium difficile-associated diarrhea. Patients are frequently administered the drugs in intensive care as a protective measure against ulcers, but this use is also associated with a 30% increase in occurrence of pneumonia. Other side effects may include bone rebuild interference and B12 vitamin reduction. In the past few years, proton-pump inhibitors, especially omeprazole have emerged as an important cause of acute tubulointerstitial nephritis, an inflammation of the kidneys.