I have a question about proton-pump inhibitor drugs. I've heard lansoprazole reaches its maximum effect at 30 mg once a day (although some Helicobacter pylori regimens do use lansoprazole 30 mg twice a day), and that higher doses just increase side effects with no additional increase in benefit. If someone taking NSAIDs (nonsteroidal anti-inflammatory drugs) needs greater gastric protection, would it be more sensible to use a higher dose of omeprazole rather than increasing the lansoprazole to twice a day?

P.

There are currently two proton-pump inhibitor drugs available for use in the United States: omeprazole (Prilosec) and lansoprazole (Prevacid). These medications act on the cells in the stomach to prevent acid production, and are the most potent medications available for this purpose.

Although the companies producing these drugs each claims its product is more effective with less side effects, in practice, gastroenterologists tend to use them interchangeably. I am not aware of any research that has demonstrated any significant clinical differences between these medications.

Studies on how the body metabolizes proton-pump inhibitors found once-a-day dosing was sufficient to maintain their effectiveness. The maximum dosage needed was also established at about 40mg for omeprazole and 30mg for lansoprazole.

However, in daily practice, gastroenterologists have noted many patients require twice-daily doses of these drugs. Such patients may include those with severe GERD (gastroesophageal reflux disease), gastric/duodenal ulcers, or Helicobacter pylori infection in the stomach. Even at higher doses, the side effects of proton-pump inhibitors are minimal -- most commonly headache and diarrhea.

Protecting the stomach from the harmful effects of nonsteroidal anti-inflammatory drugs (NSAIDs) is a different issue. NSAIDs, such as aspirin, ibuprofen and naproxen, are commonly used to relieve pain and arthritis symptoms. Unfortunately, they have a side effect of weakening the stomach's protective lining, leading to injury and ulceration in the stomach and upper intestine, or duodenum.

Several medications are useful in preventing duodenal ulcers associated with NSAIDs. However, only misoprostol (Cytotec) and proton-pump inhibitors have been shown to prevent NSAID-related ulcers in both the duodenum and the stomach. Since proton-pump inhibitors have fewer side effects than misoprostol, they are increasingly being used to protect the stomach and upper intestine from the harmful effects of NSAIDs. The largest study on this topic showed that omeprazole was about 75 percent effective in preventing ulcers at both the 20mg and 40mg doses given once a day.