Less than three months after two powerful diet drugs with a tendency to blow out heart valves were yanked from the market, the Food and Drug Administration has approved a new concoction that’s a lot different — it’ll just send your blood pressure through the roof.

High blood pressure — hypertension — as in stroke, heart attack, kidney damage. As in the very health problems the seriously obese are seeking to prevent by taking a drug that promotes rapid weight loss.

The new drug, brand name Meridia, is disturbingly similar to the banned fenfluramine and Redux (and the popular combo fen-phen). The old stuff fooled patients into thinking they were full by boosting production of the brain chemical serotonin. The new one pulls basically the same trick by slowing the body’s dissipation of serotonin. Either way, there’s a lot of extra serotonin sloshing around, which might not be a problem if extra serotonin weren’t a primary suspect in the heart valve caper.

Meridia’s maker, Knoll Pharmaceutical, wisely advises that the drug be used only short-term to jumpstart the lifestyle modification — a diet and exercise program — a severely obese person needs to get out of danger and that patients get regular checkups while on the drug. The same advice the makers of fenfluramine and Redux gave. The same advice that was ignored.

This would be the concern only of those who’d rather roll the dice on a drug than eat better and get a little exercise if everybody who pays for health insurance wouldn’t get stuck with the tab. Brand-new drugs are expensive, as are heart operations and kidney transplants, but they’re covered. Education programs to teach healthy eating and modest exercise are a lot cheaper, but rarely reimbursed.

This says a lot, none of it good, about this country’s approach to health care, about the lip service given to preventative care. Certainly, there is a place for drugs such as this; some severely obese people need a quick weight loss to avoid an imminent catastrophe, many need a boost to get hooked on a diet and exercise regime. But the public clamor for a fen-phen replacement since the day it was banned, the jubilation greeting Meridia, strongly suggests this is a society looking for the easy way out. And the home blood-pressure kits those who clamor say will keep them from keeling over while crossing the street are, medical experts agree, about as accurate as a $3 watch.

Worse still is that the FDA’s rush to approve the drug — over the objections of its own staff, incidentally — demonstrates the extreme pressure it is under to shed its anti-business label and to prevent any further attempts by Congress to abolish it. If ever there was a government agency that should be immune to the pressure of the public and Congress, it is the FDA.

High blood pressure sounds less troublesome than shredded heart valves, but it’s serious, it’s a killer. Serotonin clearly is a chemical that doesn’t like being tampered with. It’s not nice to fool Mother Nature and it’s not smart to make the same mistake twice.