Dear Cecil: When I buy over-the-counter pharmaceuticals from our local drug store, I always buy the house brand. The active ingredients and dosages in Tylenol (acetaminophen) are identical to that of the copy. The same is true of the Motrin alternative, the Sudafed clone, and so on — and they're all much cheaper. However, my wife insists on buying a brand name — she thinks I'm some kind of cheapskate. If the active ingredients in these drugs are the same, is there any difference in the quality of a brand name versus a house brand? Dave C., Wisconsin

Cecil replies:

Let’s put it this way: the differences are small. That doesn’t mean they aren’t important. It also doesn’t mean they are.

When the patents on a name-brand drug expire and competitors flood the market with knockoffs, prices can drop to astounding depths. In a quick survey of ten common drugs, my assistant Una found generics offered savings of 15 to 94 percent off name-brand prices, with the average around 60 percent. (The most dramatic difference, for you anxious types: Valium versus generic diazepam.) That’s in line with an FDA analysis, which found that having just two competing manufacturers for a drug chopped the price in half. Not surprisingly, generics are used for nearly two-thirds of all U.S. prescriptions.

The key issue in name brands versus generics is quality control. Branded drugs are tested extensively for effectiveness, side effects, and drug interactions — a slow, expensive process — and before the Waxman-Hatch Act of 1984, so were generics. The new law lowered the bar. Generic drug makers now must merely show that they use approved manufacturing processes and that the active ingredients in their products are bioequivalent to those in branded drugs — that is, that they’ll perform the same way in the human body. To consider two drugs bioequivalent, the FDA requires reasonable but not exceptional confidence that they’ll be within 20 to 25 percent of each other in terms of how much shows up in your bloodstream. So there’s room to cut corners, if you’re so inclined.

How much difference might there be, then? Una, always game for an experiment, immediately fired up the Bunsen burners, but unfortunately we’d blown the research budget on liquid analgesics. (You can’t beat a Leinie’s for long-lasting relief of a tension headache.) So instead we repaired to the med library and established the following:

One study found generic versions of the heart disease drug digoxin were 40 percent more likely to have “adverse events” than branded digoxin.

Two studies of the epilepsy drug phenytoin found wide variation in the amount of medication delivered to the blood by branded versus generic versions — the drug concentration must fall within a narrow range to be effective. A survey of epileptics who switched from branded to generic drugs found that more than 10 percent experienced reoccurrence of seizures. After the heartless socialists running Ontario’s health care system forced epileptics to take generic versions of the antiepileptic drug Lamictal, more than one in eight were switched back under doctor’s orders due to problems.

Generic diazepam was found to have a significantly slower absorption rate than Valium — if you’re waiting desperately for the stuff to kick in before boarding an airplane, it’s small comfort to know you’re saving big bucks. The antipsychotic medication clozapine has shown significant differences between generic and branded versions; in one study some patients suffered psychotic relapses after switching to generics. And research suggests generic versions of the blood thinner heparin are so different they can’t be safely substituted for one another.

You can find plenty of arguments for why generic drugs might be inferior to name brands despite using the same active ingredients. Many drugs don’t dissolve well in water and require the addition of what are known as wetting agents to improve their solubility. If the manufacturer of a generic substitutes a cheaper but less effective agent, too bad for you. The brand-name drug maker Merck, assuredly a biased source, recommends against substitution of generics when small differences in dose cause a big difference in effect, as with blood thinners like warfarin. Merck also raises the possibility that different inactive ingredients could cause allergic reactions.

Still, let’s note the obvious: most of the drugs we’ve been talking about here are used to treat serious conditions. They’re not really an argument for buying name-brand cough syrup. The effectiveness of any drug varies with the individual. If you’re the methodical sort and the worst that could happen with a generic is your sniffles last longer, the logical approach is to find the cheapest thing that works. Then again, judging the effectiveness of over-the-counter drugs is often subjective, and I’m guessing your wife won’t sit still for a double-blind test. If so, you might simply point out that in relatively low-stakes situations, at least, heard of it + costs more = good is an assumption that favors marketers, not the rest of us.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.