Monday, October 6, 2008

Generics and Allergies Redux

I've covered generic drugs and their supposed inferiority to brand-name drugs before. But something came up at work the other day that made me want to take a second look at the topic.

Scenario: Male patient, age I forget, military (so he has Tricare insurance, which pays for everything except for the things that it doesn't). A middle-aged woman is driving him around and apparently in charge of his care (wife? mother? again, I forget the guy's age).

Four new prescriptions. Metoprolol XL (beta-blocker), raniditine (antacid), warfarin (Coumadin, anticoagulant/"blood thinner"), furosemide (diuretic/fluid mobilizer). All new meds for him. I guessed post-heart attack or maybe heart failure, but didn't actually ask what was wrong.

Doctor signed the Coumadin script dispense as written. Tricare won't pay for brand-name Coumadin for this patient. Other three drugs come back $0. Zero, zip, nothing, free. Coumadin comes back $55. The patient has two options: Wait for someone to call the doc tomorrow and get authorization to dispense generic or pay for the brand. For $55, I'll tell you what I'd do. He didn't; he paid the $55. Why?

"His doctor is very particular, and he has a lot of allergies, so he's going to go with the brand name. He might be allergic to one of the fillers in the generic, you know."

To the credit of the woman managing his care, she was actually pretty smart. She asked a lot of good questions and knew a thing or two about the medicines she and some of her family members were on. Best kind of patient. But here was an example of what she knew getting her in trouble, and she wouldn't be talked out of it. I had previously explained to her that it didn't matter whether he went brand or generic as long as he stuck with his choice (warfarin is a fickle mistress, and you want to be consistent).

I'd heard this line of reasoning before--once from a patient and once from a tech I used to work with. "I might be allergic to the fillers in the generic."

News flash. You might be allergic to the fillers (excipients) in the brand, too. There are probably only about two dozen different ingredients that you can put into tablets and have them still do what they're supposed to do. The brand and the generic probably differ by only one or two excipients. If you've never taken either one, you are just as likely to be allergic to a component of the brand as the generic. Generic drugs are not made with ingredients that are somehow more likely to be immunogenic.

So. Unless you know you're allergic to something (a dye, for example) and you know the brand or generic version of a particular drug contains that something there's no reason to assume you are "less likely" to be allergic to something in the brand name drug.

Another day, another victory. Generics are still the way to go, 99.999% of the time.


Dubito said...

This has always intrigued me.

My background is psychology, but my parents were both pharmacists, so I consider myself to know more than, say, 95% of the population about drug safety, usage, effects, etc.

I then had a very intense rapid learning thrust upon me by being the information/research/advice officer for a disability-sector brain injury organisation.

During which I had long-term contact with the wife of one man who had severe behavioural issues triggered by elevated body heat from dysautonomia: In fact, the treatment when his mood could be caught early was to stand by the sink and pour cold water over his head.

And then one day the pharmacist in town (an hour's drive away) dispensed him a generic instead of his usual anti-epileptic, and he had "a reaction" and his wife had to call the police for her own protection.

The only thing I can think of is that the stress of not getting the medication he relied upon to keep him stable was the trigger, not the medication itself.

TheAngriestPharmacist said...

Most people start with Coumadin 5mg tablets and adjust from there. Let's analyze the excipients for giggles.

Coumadin 5mg (Bristol): FD&C Yellow No. 6, Lactose, Magnesium Silicate, Magnesium Stearate, starch.

Coumadin 5mg (NuCare): FD&C Yellow No. 6, Lactose.

Jantoven 5mg (Upsher): FD&C Yellow No. 6, Lactose, Magnesium Stearate, Povidone, Pregelatinized Corn Starch.

Warfarin 5mg (Barr): FD&C Yellow No. 6, Lactose, Hypromellose, Magnesium Stearate, Pregelatinized Starch.

Warfarin 5mg (PD-RX): Corn Starch, D&C Red No. 6, D&C Yellow No. 10, Lactose, Magnesium Stearate. NOTE: TARO Brand uses same excipients as PD-RX.

There are some others, but Barr is the biggest -- and what's used pretty universally (at least everywhere I've ever worked). I'm betting Taro would be second most used generic.

Anyway -- what's the big fucking deal here? I can understand dyes. That's rare, and those people aren't wishy-washy. "Well, I dunno, my doctor said this. I could be allergic."

People with Dye Allergies know, because they spent years figuring it out. "Here's a prescription for X product. I am allergic to FD&C Red No.3, Blue No. 9, and codeine. They all cause X symptom."

Anyone else is full of shit.