drug interactions – Real Life Pharmacology

April 9, 2020April 8, 2020

Calcium Acetate Pharmacology

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Calcium Acetate (PhosLo) is used in the management of hyperphosphatemia associated with CKD.

Important monitoring parameters for calcium acetate include phosphorus, calcium, PTH, and renal function.

There are numerous binding interactions with calcium acetate. It can reduce concentrations of some HIV drugs, antibiotics, and thyroid supplements. I discuss more examples in the podcast.

Thiazide diuretic in combination with calcium acetate may increase the risk for hypercalcemia.

I also discuss drug interactions on the podcast, be sure to check out my latest project which is a 200+ page book on managing drug interactions in primary care.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

April 2, 2020April 1, 2020

Nortriptyline Pharmacology

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Nortriptyline is a TCA that can be used for depression and various pain syndromes. I discuss other less common diagnoses in this podcast episode as well.

There are a lot of drug interactions with nortriptyline. It is metabolized by CYP2D6, can have additive anticholinergic effects and has been associated with QTc prolongation.

Nortriptyline is very anticholinergic and can blunt the effects of dementia medications.

Dry mouth, dry eyes, sedation, urinary retention, and constipation are a few of the more common adverse effects of nortriptyline.

I also discuss drug interactions on the podcast, be sure to check out my latest project which is a 200+ page book on managing drug interactions in primary care.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

February 13, 2020February 6, 2020

Diltiazem Pharmacology

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Diltiazem is a non-dihydropyridine calcium channel blocker that can be used in atrial fibrillation as well as hypertension.

One big downside to diltiazem is that it does have a few drug interactions via CYP3A4.

Aripiprazole, apixaban, and certain statins are all examples of medication that can have concentrations increased by adding diltiazem to a patient’s regimen.

Diltiazem works a little differently from dihydropyridine calcium channel blockers (like amlodipine) as it works on the heart AND the vessels.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

February 6, 2020February 5, 2020

Zolpidem Pharmacology

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Zolpidem enhances the action of GABA which is an inhibitor neurotransmitter.

Zolpidem metabolism can be impacted by the use of CYP3A4 inhibitors. Concentrations can rise on account of this potential interaction.

It is important to remember to go slowly when tapering off zolpidem. Particularly in patients who have been on the drug for a long time or those who are on higher doses.

Abnormal sleeping behaviors like sleep-walking, eating, or driving have been reported with zolpidem.

Remember that CNS depressant drug interactions can happen with zolpidem. Take note of any other sedating medications prior to starting zolpidem.

I also discuss drug interactions on the podcast, be sure to check out my latest project which is a 200+ page book on managing drug interactions in primary care.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

November 21, 2019November 20, 2019

Metronidazole Pharmacology

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Metronidazole (Flagyl) is an antibiotic that is used for various infections.

Metronidazole can certainly cause GI upset like most antibiotics, but uniquely may also cause a metallic taste.

Metronidazole is also rarely associated with CNS changes and can induce the potential for peripheral neuropathy.

Patients should avoid alcohol with the use of metronidazole and this is on account for the possibility of a disulfiram reaction. I discuss some of the symptoms of this reaction in the podcast.

Metronidazole can substantially raise the concentrations of warfarin. INR monitor and a reduction in dose of warfarin may be necessary.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

October 24, 2019October 22, 2019

Mirabegron Pharmacology

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Mirabegron is a beta-3 agonist that can help relax bladder smooth muscle and manage symptoms of overactive bladder.

Mirabegron inhibits CYP2D6 which can negatively impact the effectiveness of tamoxifen. I discuss this in greater detail in the podcast.

Tramadol and codeine effectiveness can be impacted by mirabegron. Be aware of this when using this medication.

By inhibiting CYP2D6, mirabegron can increase the concentrations of many psychotropic medications such as fluoxetine, aripiprazole, clozapine, and paroxetine. I discuss this further in this episode of the podcast.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

July 11, 2019July 2, 2019

Cimetidine Pharmacology

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Cimetidine blocks histamine 2 receptors which can suppress acid production and reduce symptoms of heartburn.

One of the major downsides to cimetidine is that it has a ton of drug interactions. I discuss many of the common ones in this episode.

Cimetidine is one of a few drugs that has the potential to cause gynecomastia. I discuss the mechanism of this adverse effect in this episode.

Phenytoin concentrations can rise due to the use of cimetidine. I discuss this in the drug interactions section of this episode.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

May 23, 2019May 17, 2019

Clozapine Pharmacology

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On this episode, I discuss clozapine pharmacology. This drug has multiple mechanisms of action: Dopamine blockade, anticholinergic activity, and alpha blocking activity all contribute to the complexity of this drug.

Smoking cessation can significantly increase the concentrations of clozapine. This is because smoking can induce CYP1A2. Listen to the podcast for more details on how this can impact our patients clinically.

Clozapine has 5 boxed warnings. I discuss them all in this podcast. The most well-known boxed warning is for agranulocytosis.

Because clozapine has alpha blocking activity, it can cause orthostasis. We need to monitor for this.

Clozapine can cause QTc prolongation. Keep an eye out for other medications that the patient may be taking that can also cause this. Examples include: amiodarone, ondansetron, quinolones, and macrolides

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

May 16, 2019August 25, 2019

Carbamazepine Pharmacology

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On this episode, I discuss carbamazepine pharmacology. This drug is most commonly used for seizures, bipolar disorder, or trigeminal neuralgia.

Carbamazepine is an autoinducer and can reduce the concentrations of numerous drugs. Some examples include apixaban, warfarin, rivaroxaban, diltiazem, verapamil, and many more!

Carbamazepine has the potential to cause Steven Johnson’s Syndrome. This has a much greater chance of happening in patients with certain genetics.

Carbamazepine can contribute to SIADH and cause significant hyponatremia.

Carbamazepine has boxed warning for numerous potential events like aplastic anemia, agranulocytosis, and the above-mentioned SJS.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!

January 31, 2019January 29, 2019

Trazodone Pharmacology

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Trazodone pharmacology is complex. It can inhibit serotonin reuptake, block histamine receptors, and possibly have alpha-blocking activity.

Side effects of trazodone include sedation, dizziness, and dry mouth. Rarely, priapism may occur. I’ve seen this nugget come up on pharmacology exams!

While trazodone is classified as antidepressant, it is often used to help manage insomnia.

Trazodone can possibly prolong the QT interval. Risk of other medications and patient specific parameters should be considered.

Trazodone concentrations can be increased with the use of CYP3A4 inhibitors and reduced with 3A4 inducers.

Be sure to check out our free Top 200 study guide – a 31 page PDF that is yours for FREE!