Pantoprazole

           Pantoprazole is used to treat gastroesophageal reflux disease (GERD), a condition in which backward flow of acid from the stomach causes heartburn and possible injury of the esophagus (the tube between the throat and stomach). Pantoprazole is used to treat the symptoms of GERD, allow the esophagus to heal, and prevent further damage to the esophagus. It is also used to treat conditions where the stomach produces too much acid, such as Zollinger-Ellison syndrome. Pantoprazole is in a class of medications called proton-pump inhibitors. It works by decreasing the amount of acid made in the stomach.

Pharmacokinetics
Understanding the pharmacodynamics of the PPIs is more relevant than knowing their pharmacokinetic parameters, since the duration of action depends on the rate of de novo proton-pump regeneration, not the duration of drug circulating in the body. Although the mean plasma half-life (t 1/2) after a single 40-mg intravenous dose of pantoprazole is 1.0 hour (range, 0.8 to 1.3 hours), a steady state of acid secretion does not occur until after approximately three days of once-daily dosing because a balance develops between synthesis of new enzyme and drug inhibition of existing ATPase. Pantoprazole is acid unstable and is thus prepared as an enteric-coated tablet, which should not be crushed. Its absorption is rapid, and the maximum concentration occurs approximately 2.5 hours after single or multiple oral 40- mg doses. Pantoprazole is well absorbed, undergoes limited first-pass metabolism, and has an absolute bio-availability of approximately 77%. The drug may be taken without regard to meals or antacids. Its apparent volume of distribution (V) is approximately 11.0 to 23.6 L, and the serum protein binding is ~98%. Pantoprazole is extensively metabolized in the liver through the cytochrome P-450 system, predominantly by CYP2C19 demethylation with subsequent sulfation and has a serum elimination half-life of about 1.1 hours. Pantoprazole does not accumulate, and its pharmacokinetics are not altered by multiple daily dosing. No dose adjustments are recommended in geriatric patients or those with renal failure or mild to moderate hepatic failure. In patients with severe liver cirrhosis, the half-life is somewhat prolonged to seven to nine hours. Pharmacokinetic data for individuals under 18 are not available.

A pharmacokinetic trial evaluating single intravenous doses in healthy volunteers found that 20- mg, 40-mg, and 80-mg doses exhibited a linear relationship in regard to the primary pharmacokinetic characteristics of area under the curve and maximum concentration. The t 1/2, clearance, and V were consistently not influenced by different doses and were similar to the pharmacokinetic parameters noted earlier for oral administration.

A clinical trial in healthy volunteers found equipotent inhibition of gastric acid secretion by equal doses of oral or intravenous pantoprazole. The primary parameter for the equivalence analysis was the percentage of time at which the intragastric pH was at least 4 or higher. The secondary parameter was the percentage of time at which the intragastric pH was at least 3 or higher. Clinical efficacy and pharmacodynamic equivalence of oral and intravenous 40-mg doses of pantoprazole have also been demonstrated in patients with erosive esophagitis.

Uses
1. Gastro oesophageal reflux disease, including treatment of symptoms such as heartburn, acid regurgitation and pain on swallowing and long-term management of reflux oesophagitis.
2. Treating peptic ulcers.
3. Preventing peptic ulcers in people who need continued treatment with non-steroidal anti-inflammatory painkillers (NSAIDs) and are at risk of ulcers.
4. Eradicating a type of bacteria called Helicobacter pylori from the gut of people with a peptic ulcer (in combination with antibiotics).
5. Excessive secretion of stomach acid due to a tumour or enlargement of the pancreas (Zollinger-Ellison syndrome).

Side Effects
- Abdominal or stomach pain
- Blurred vision
- Headache
- Dry mouth
- Flushed, dry skin
- Fruit-like breath odor
- Increased hunger
- Increased thirst
- Increased urination
- Nausea
- Sweating
- Troubled breathing
- Unexplained weight loss
- Vomiting

Dosage
Adults : 40 mg     Once or twice daily for up to 8 weeks*

Contraindications
 Pantoprazole is contraindicated in conditions like Hypersensitivity.

Warning!
1. Stomach cancer can have similar symptoms to stomach ulcers, and these symptoms can be relieved by pantoprazole. For this reason, if it is suspected that you have a stomach ulcer, your doctor should exclude the possibility of stomach cancer before you start treatment with this medicine. Otherwise, this medicine could mask the symptoms of stomach cancer and therefore delay diagnosis of this condition. This is particularly important if you are middle aged or older and have new or recently changed symptoms.
2. As pantoprazole decreases the acidity in the stomach, it may lead to a slightly increased risk of getting stomach infections such as Salmonella and Campylobacter.
3. If you are taking a proton pump inhibitor medicine such as this one for longer than three months it may cause the level of magnesium in your blood to fall. This is more likely if you are also taking digoxin or a diuretic medicine (see end of factsheet). Symptoms of low magnesium can include fatigue, muscle spasms or twitching, convulsions, disorientation, dizziness and increased heart rate. You should tell your doctor if you experience any of these symptoms, as your level of magnesium may need to be checked and corrected.
4. Proton pump inhibitor medicines such as this one, particularly if taken in high doses for longer than a year, may slightly increase the risk of breaking a bone in your hip, wrist or spine. If you are elderly, or have osteoporosis or risk factors for getting osteoporosis, it is important to make sure that you have an adequate intake of calcium and vitamin D to avoid any problems with your bones. Your doctor may want you to take calcium and vitamin D supplements if you don't get enough in your diet. Ask your doctor for further advice.
5. If you have any liver problems, your liver function should be monitored regularly while you are having treatment with this medicine.
6. In people having long-term treatment with this medicine, eg for Zollinger-Ellison syndrome, the medicine may reduce the absorption of vitamin B12 (cyanocobalamin) from the gut into the bloodstream. Ask your doctor for more information or advice about this.



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