Antifungal Drug Interactions: Contraindications, Black Box Warnings, and Nursing Implications

00:00 Your understanding of drug interactions is critical for your patient's safety, especially with the oral antifungals. For topical antifungals, interactions are generally minimal due to limited systemic absorption. However, there are some exceptions. If a topical is applied to a large surface area, some absorption can occur. Ketoconazole can interact with oral anticoagulants, and myconazole can interact with warfarin, increasing the anticoagulation effects.

00:29 Now, oral terbinophine is a moderate inhibitor of the CYP2D6, and it can interact with these medications. Beta-blockers. This can potentially increase the effects of the beta-blockers. Antidepressants like TCAs and SSRIs could increase their levels when used with oral terbinophine. And finally, antipsychotics with oral terbinophine could potentially cause increased side effects.

00:57 Itraconazole is particularly concerning because it's a strong CYP3A4 inhibitor.

01:04 Now, this can give us numerous significant interactions. So, itronicazole with statins, that could drastically increase the risk of muscle damage.

01:13 If you give them with benzodiazepines, this could lead to excessive sedation.

01:18 What about itraconazole and calcium channel blockers? Well, this could potentially cause dangerous hypotension. This medication with warfarin will increase the bleeding risk.

01:29 This medication, with oral hypoglycemics, can potentially cause hypoglycemia, and there are several others. But those are the most important ones I wanted to bring to your attention.

01:39 So, how are you going to apply this knowledge in your healthcare practice? Well, hopefully, we've made you see the importance of a thorough medication reconciliation.

01:50 It is essential before these medications are started. So, before an oral antifungal is started, you want to make sure you have a complete and accurate medication reconciliation. You have to be vigilant for signs of interactions. You'll need to educate the patients about the potential warning signs and communicate any concerns promptly to the healthcare team. Now, there's FDA black box warnings and contraindications for the antifungals. And I want to talk about the most serious safety concerns with the oral antifungals. These guys have earned the FDA black box warning. Now, for oral terbinophine, it's contraindicated in patients who have active or chronic liver disease. Serious or even fatal hepatic injury has been reported in patients with and without pre-existing liver disease. So, that's why monitoring for signs of any liver dysfunction is so critical to keep your patients safe. For oral itraconazole, there are two major black box warnings. The first one, there's a heart failure risk due to the negative inotropic effects.

02:55 So, it's contraindicated in patients with heart failure, and it can worsen existing heart failure or precipitate it in vulnerable patients. The second one are serious drug interactions. Remember, it has this strong inhibition of the CYP3A4. This is what can increase the level of other medications to dangerous or even life-threatening levels. So, that's why this medication is contraindicated with certain drugs. Now, here's some examples. It's absolutely contraindicated with penazide, quinidine, dofetilide, and cisapride because this increases the risk of life-threatening arrhythmias. It's contraindicated with lovastatin and simvastatin due to the risk of rhabdomyolysis and it's contraindicated with ergot alkaloids due to the risk of ergotism.

03:42 So, let's take another question. What assessment findings would make you concerned about a potential drug interaction or adverse effect in a patient taking itraconazole? You'd watch for irregular heartbeat or palpitations with QT prolonging drugs, muscle pain with statins, and signs of peripheral vasospasm with ergot alkaloids.

04:05 It's your vigilance in these assessments that's crucial for preventing serious adverse outcomes.