Funny, but while Britain's regulators are limiting access to top-selling Alzheimer's drug Aricept, countries elsewhere are expanding its availability. Eisai Pharmaceuticals (OTC BB: ESALY.PK), the Japanese manufacturer that co-markets the drug with Pfizer (NYSE:PFE), announced that it received approval in Japan to use Aricept to treat all forms of Alzheimer's.

Japan's regulators made the decision following a six-month study comparing Aricept with a placebo. The patients treated with Aricept showed a statistically significant improvement in cognitive function compared with those taking the placebo. Because there is no cure for Alzheimer's, treatment is limited to temporarily halting the disease's advance.

Because Britain's national health-care system pays for the medicine its citizens are prescribed, it has determined that the cost-benefit analysis just isn't worth allowing people with mild to moderate symptoms of Alzheimer's access to Aricept. Contrast that with the fact that the U.S. Food and Drug Administration -- itself an agency that moves at a glacial pace -- approved such access more than 11 years ago. It recently expanded approval to also cover moderate to severe forms of Alzheimer's, which is what Japan's regulators just did. The drug is marketed in more than 76 countries, where it is typically the only medication that covers the full spectrum of Alzheimer's symptoms.

Patients are usually prescribed one of three drugs: Aricept, Exelon by Novartis (NYSE:NVS), or Razadyne by Johnson & Johnson (NYSE:JNJ). Often they are prescribed in conjunction with Namenda, which is manufactured by Forest Labs (NYSE:FRX). They are part of a group of drugs known as cholinesterase inhibitors, which work to prevent the breakdown of an important chemical messenger in the brain.

Aricept, though, is the world's most prescribed treatment for Alzheimer's. In its most recent financial statement, released last month, Eisai -- Japan's fourth-largest pharmaceutical -- reported that worldwide sales of Aricept jumped 25% to 67.3 billion yen, with earnings growing 22% year over year.

While the cost of Aricept is high, at least one study has shown that not treating Alzheimer's actually costs more -- about 50% more. That also doesn't take into account more subjective criteria, such as the relief of caregivers (particularly family members) when an individual is able to exhibit greater cognitive skills.

Britain's policy still allows access to Aricept in the more severe stages, but won't pay for it in the earlier stages. It therefore forces people to deteriorate greatly before they can get access to drugs that alleviate some of the ravages of the disease. Rationing and limitations are an ever-present threat to patients, which is something worth remembering as the debate over national health care gains greater visibility here because of presidential politics.

For related Foolish articles:

Johnson & Johnson is recommended in Motley Fool Income Investor, and Pfizer is recommended in Inside Value. A 30-day free trial is available to any of our newsletter services.

Fool contributor Rich Duprey owns shares of Eisai but does not have a financial position in any of the other stocks mentioned in this article. You can see his holdings here. The Motley Fool has a disclosure policy.