The P-I-E-N-O Parkinsn's List Drug Database

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lansoprazole / PrevacidTM , TakedaTM

ANTIULCER:

Description: Lansoprazole is an antiulcer drug similar to omeprazole. Like omeprazole, lansoprazole is an acid proton-pump inhibitor. It is used for the short-term treatment of duodenal ulcers or erosive esophagitis, and for long-term treatment of a pathological hypersecretory condition known as Zollinger-Ellison syndrome. Lansoprazole is at least as effective as omeprazole in treating peptic ulcers and reflux esophagitis, and it has been shown to relieve reflux symptoms more quickly than either omeprazole or ranitidine.DD Over a 4-week period, ulcer healing was greater with lansoprazole than ranitidine or placebo in a double-blind study of the treatment of active duodenal ulcer.DĽ A comparative study of omeprazole and lansoprazole in the short-term treatment of reflux esophagitis showed no significant difference in healing after 4 or 8 weeks. Lansoprazole, however, showed greater improvement in heartburn and acid regurgitation symptoms after 4 weeks.D Lansoprazole has also been demonstrated to be safe and effective for chronic therapy of Zollinger-Ellison syndromeD and for Barrett's esophagus.D Lansoprazole was approved by the FDA in May 1995. It currently is not approved for maintenance therapy of esophagitis or duodenal ulcers.

Mechanism of Action: Lansoprazole inhibits gastric acid secretion. It belongs to a new class of antisecretory agents, the substituted benzimidazoles, which suppress gastric acid secretion by inhibiting the H+/K+ ATPase enzyme system of gastric parietal cells. A significant increase in gastric pH and decrease in basal acid output follow oral administration of lansoprazole. In hypersecretory conditions, lansoprazole has a marked effect on gastric acid secretion, both basal-and pentagastrin-stimulated. Lansoprazole exerts an inhibitory effect on gastric acid for at least 24 hours, which allows a once-daily dosing schedule. Lansoprazole does not antagonize HA or cholinergic receptors.

Serum gastrin levels increase 50-100% from baseline in the fasting state, and these increases are greater during lansoprazole therapy than during ranitidine therapy.DĽ Increases reach a plateau within 2 months and return to pretreatment levels within 4 weeks of discontinuation of lansoprazole therapy. Although prolonged hypergastrinemia has been associated with gastric tumors, a long-term study of lansoprazole for the treatment of Zollinger-Ellison syndrome did not reveal evidence to suggest that lansoprazole was implicated in tumor progression noted in two (10% of) patients.D Both patients already had extensive metastatic disease.

Short-term (i.e., 8-week) studies showed that lansoprazole had no effect on the endocrine system. Like omeprazole, however, lansoprazole also inhibits the hepatic cytochrome PAŽ¨ oxidase system (see Drug Interactions).

Pharmacokinetics: Lansoprazole is administered orally and should be taken before meals on a once-daily schedule, unless large doses are used for hypersecretory conditions. The capsules contain enteric-coated granules that release drug after they leave the stomach. Absorption is rapid; mean peak plasma levels occur after about 1.7 hours. The absolute bioavailability is over 80%, which can be reduced by 50% if lansoprazole is given 30 minutes after food. Lansoprazole is about 97% bound to plasma protein. Lansoprazole is excreted into animal breast milk and possibly into human breast milk. It is believed to be transformed into two active inhibitors of acid secretion in the gastric parietal cells.

Hepatic metabolism of lansoprazole is extensive. The two identified hepatic metabolites of lansoprazole have little antisecretory activity. Plasma elimination half-life, which is less than 2 hours, is not related to gastric antisecretory effect, which lasts more than 24 hours. Elderly patients have an increase in elimination half-life of up to 2.9 hours, but accumulation was not observed in these patients during once-daily dosing. Elimination half-life can be delayed as long as 7 hours in patients with hepatic impairment.

Elimination is believed to occur via biliary excretion. Almost no unchanged lansoprazole is detected in urine after single-dose administration. After administration of a single dose of radio-labeled lansoprazole, one-third of the administered radiation was excreted in urine and two-thirds in the feces. Patients with impaired renal function showed no differences from healthy subjects. Hepatically impaired patients, however, had increases in mean AUC of up to 500% and could require reduced doses. No differences were determined between male and female groups. There have been no studies of lansoprazole use in children.

CONTRAINDICATIONS/PRECAUTIONS: Animal studies have indicated that lansoprazole is excreted into breast milk. Although no studies have been done to determine if lansoprazole is similarly excreted into human milk, lansoprazole use is not recommended during breast-feeding.

Lansoprazole is classified as pregnancy category B. Animal studies have shown no teratogenic effects. Adequate studies have not been undertaken in humans. Lansoprazole should be used during pregnancy only when clearly needed.

Lansoprazole elimination half-life is significantly prolonged in patients with hepatic disease. Patients with severe hepatic disease might require a dosage adjustment. Abnormal liver-function tests have been reported with lansoprazole use (see Adverse Reactions). In elderly patients elimination half-life is increased between 50 and 100%. A suggested ceiling of 30 mg of lansoprazole per day in the elderly is suggested, once the initial dosing regimen is complete.

Safety and efficacy of lansoprazole have not been established in children.

DRUG INTERACTIONS: Sucralfate has been shown to delay absorption and reduce the bioavailability of lansoprazole. Lansoprazole should be taken no less than 30 minutes before sucralfate if these drugs are to be used concomitantly.

Lansoprazole is metabolized by the cytochrome PAŽ¨ system. It has been shown that one of the specific isozymes responsible is CYP3A, which is also a factor in the metabolism of theophylline. Concomitant use of theophylline and lansoprazole has caused a small increase (10%) in the clearance rate of theophylline. Therapy with theophylline could require adjustment when therapy with lansoprazole is stopped or started. Other drugs metabolized through the PA¨ system require different isozymes. No interactions have been reported between lansoprazole and warfarin, antipyrine, indomethacin, ibuprofen, phenytoin, propranolol, prednisone, or diazepam in healthy subjects.

Lansoprazole has a long-lasting effect on the secretion of gastric acid. For drugs whose bioavailability is influenced by gastric pH, the concomitant administration of lansoprazole can exert a significant effect on their absorption. Drugs that could be affected by lansoprazole in this way include ampicillin, digoxin, iron salts, and ketoconazole.

Long-term treatment with lansoprazole in conjunction with diazepam therapy has been studied. Plasma elimination half-life, clearance, and volume of distribution of diazepam were not affected by concurrent use of lansoprazole.D

A multiple-dose, placebo-controlled, randomized two-way crossover study investigated the use of lansoprazole with a low-dose oral contraceptive containing ethinylestradiol and levonorgestrel. The bioavailability of oral contraceptives was not affected by lansoprazole.D

ADVERSE REACTIONS: Lansoprazole appears to have few adverse reactions. The only reactions attributed to a causal relationship with lansoprazole were abdominal pain, diarrhea, and nausea/vomiting. The incidence of diarrhea as a side effect increases with an increase in dosage. According to the manufacturer, at a daily dose of 60 mg of lansoprazole, 7.4% of patients suffered diarrhea compared with 2.9% in the placebo group.

Headache was reported in more than 1% of patients taking lansoprazole, but a higher percentage of patients taking placebo reported headache, so a causal relationship to lansoprazole is questionable. Other adverse reactions reported with lansoprazole occurred in <1% of patients.

PATIENT INFORMATION:

What do lansoprazole capsules do?

Lansoprazole (PrevacidTM ) prevents the production of acid in the stomach, reducing symptoms and preventing injury to the esophagus, stomach, or intestines. Lansoprazole heals active duodenal ulcers, and is useful in conditions that cause excessive stomach acid production such as Zollinger-Ellison syndrome. Generic lansoprazole capsules are not yet available.

What should my doctor, dentist, or pharmacist know before I take lansoprazole?

They need to know if you have any of these conditions:

How should I take this medicine?

Take lansoprazole capsules by mouth. Follow the directions on the prescription label. Swallow the capsules whole with a drink of water; do not crush or chew. Lansoprazole works best if taken on an empty stomach. It is best to take the capsules 30 to 60 minutes before food. Take your doses at regular intervals. Do not take your medicine more often than directed.

Elderly patients: It may take elderly patients longer to remove this medicine from the body. Elderly patients should not take more than 30 mg of lansoprazole per day.

Special precautions for use in children:

This medicine is not for use in children.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What other medicines can interact with lansoprazole?

Tell your doctor or pharmacist: about all other medicines you are taking, including non-prescription medicines; if you are a frequent user of drinks with caffeine or alcohol; if you smoke; or if you use illegal drugs. These may affect the way your medicine works. Check before stopping or starting any of your medicines.

What side effects may I notice from taking lansoprazole?

Side effects with lansoprazole have been few and not of a serious nature. They include:

Let your doctor know about these side effects if they do not go away or if they annoy you.

What do I need to watch for while I take lansoprazole?

It can take several days of therapy with lansoprazole before your stomach pains improve. Check with your doctor if your condition does not improve, or if it gets worse. Do not take for more than 4 weeks for duodenal ulcer, or more than 8 weeks for esophagitis withour checking with your doctor. You can take antacids for the occasional relief of pain unless your doctor tells you otherwise.

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15 and 30C (59 and 86F). Protect from moisture. Throw away any unused medicine after the expiration date.

The P-I-E-N-O Parkinsn's List Drug Database Index

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