What is the pharmacist responsibility regarding drug interaction?

Am I expecting too much, or did this pharmacist fall short of performing her duty? She caught the interaction, checked that the dentist had been apprised of the anti-coagulant medication and deferred to the dentist's expertise. I think this is more the dentist's cockup than the pharmacist's. Drug interactions are a tricky area. If you go looking for them (on the many websites that exist for that purpose) you'll find that an awful lot of drugs that are fairly commonly prescribed are known to present at least some risk of interaction, and yet doctors will frequently, and as a matter of conventional best-practice, prescribe those drugs together. Pharmacists would pretty soon be out of a job if they refused to fill every prescription for which there was a known potential interaction.

The pharmacist is not supposed to second-guess the doctor. She did her duty by noting the potentially harmful interaction, and by asking you if you discussed it with the doctor. Once you said the doctor was aware of it, it was really out of her hands.

The pharmacist did indicate some potential issues to you, although maybe not to the level of detail you now want. Of course, you could have pressed the pharmacist to tell you more about the rare interaction as well. If either of you was able to see what the future held, you both probably would have acted differently. But, the pharmacist did act within acceptable professional parameters. The real problem is with the prescribing doctor, your dentist. The dentist was told directly about your husband's other drugs, particularly the anti-coagulant. One very popular anti-coagulant (Warfarin/Coumadin) is well-known to be sensitive to other drugs and interactions can result in major complications. This property is well-known and often acts as a red flag that should trigger extra consideration by the prescribing doctor. It sounds like your dentist dropped the ball there. Tell the dentist about the major complications so that they are more careful next time with both your husband as well as their other patients. If you're looking to find the responsible party, it's the dentist. I'd also talk to the doctor who is prescribing and monitoring the anti-coagulant to make sure they're also aware of the events. Perhaps you can suggest to them that you'd like to get a green light from them whenever a new drug is prescribed - as a double-check for interactions and a prompt for more monitoring of your husband's anti-coagulant levels.

Yes, I just want to point out in agreement with MeiraV that pharmacists go through a HUGE amount of training and it's not because of how hard it is to count pills and screw on bottle tops. They are considered the last in a line of defense against human errors that can lead to situations like this. The dentist screwed up but so did the pharmacist.

But the pharmacist specifically saw the potential for a problem and recklessly went ahead with dispensing the drug. This is incorrect. The pharmacist checked that the physician was fully informed about the medications the patient was on before prescribing the antibiotics. It is simply not the case that the pharmacist is required to refuse to dispense all medications that come with warnings about potential interactions or side effects. If they were, they'd hardly dispense any drugs at all.

I can't comment on this specific situation (IANYD etc), but I suspect from what you describe that the antibiotic was one of the types that is known to interfere with the INR ("protime"). As a physician I generally try not to prescribe those antibiotics to people on warfarin, although sometimes for whatever reason, it happens. In those cases, I would appreciate a call from the pharmacist to discuss the interaction with me and to discuss the alternative antibiotics that would be appropriate - there are usually several antibiotic choices in any given case that would work. The pharmacist should have called the prescriber. I've been called for much less concerning issues in a prescription than this. That said, the ultimate responsibility always lies with the prescriber themselves who knows the patient's clinical story.

The pharmacist noticed the possibility of an adverse drug interaction; you assured her that yes, the dentist was informed of all Mr. B's current meds, and made the prescription anyway. If either of these professionals made an error, it was the dentist, NOT the pharmacist. You say that you'll talk to the dentist and be more vigilant about possible interactions; you're right to be more vigilant, but I'd suggest you also find a different dentist.

I agree, this is the dentist's responsibility, not the pharmacist's. The pharmacist did their duty by mentioning the potential interaction, but not being privy to your partner's medical history, the pharmacist assumed the doctor and/or dentist had more/better information regarding the risk involved. Especially given that you told the pharmacist that the doctor and/or dentist was aware of the anti-coagulant prescription. The dentist dropped the ball here, and I would have a chat with them about being more careful in the future and possibly coordinating with your partner's physician if you still feel comfortable sticking with them.

In terms of being more vigilant, I use http://www.nlm.nih.gov/medlineplus/druginformation.html. For each medication, it lists both conditions and drugs that can interact with them and give you a reason to check in with your doctor/dentist or pharmacist about it.