Heparin Pharmacology

Heparin Pharmacology

Heparin is an interesting drug with a lot of unique clinical quirks. This drug ultimately inhibits the formation of fibrin. Fibrin is an essential component of a blood clot.

Because heparin has blood thinning effects, it is critical to assess a patient’s bleed risk. Look out for other agents that may increase the risk of bleeding. Examples include; NSAIDs, antiplatelet agents, and other anticoagulants.

One classic test question about heparin that often comes up is the reversal agent. Protamine can be used to help reverse the effects of heparin.

Heparin-induced thrombocytopenia is a critical adverse effect to understand. I discuss both subtypes on the podcast and let you know what to look out for.

Rarer side effects of heparin include hyperkalemia and osteoporosis (only with long term use).

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Montelukast Pharmacology

Montelukast Pharmacology

On this episode, I discuss montelukast pharmacology

Montelukast is a leukotriene receptor antagonist. Leukotrienes play an important role in causing inflammation and smooth muscle contraction in asthma and allergic rhinitis.

Because montelukast blocks the effects of leukotrienes, it can be advantageous to use this medication for allergies and asthma.

It is important to remind patients that montelukast is NOT a substitute for an acute relief medication like albuterol in the management of asthma symptoms.

Montelukast has been reported to cause mood and behavioral changes and it is important to monitor our patients for these rare concerns.

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Clozapine Pharmacology

Clozapine Pharmacology

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

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Carbamazepine Pharmacology

Carbamazapine Pharmacology

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.

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Stimulant Laxatives Pharmacology

Stimulant Laxative

On this episode, I discuss the pharmacology of commonly used stimulant laxatives like sennosides and bisacodyl.

Stimulant laxatives “stimulate” the GI tract smooth muscle which helps propel fecal material out of the body and thus helping to relieve constipation.

Patients who are having diarrhea and are unsure of what medications they are taking should have their regimen assessed for these medications.

Chronic opioid therapy is a situation where chronic stimulant laxative therapy may be used.

Stimulant laxatives have very few drug interactions. However, bisacodyl effectiveness can be reduced by the use of antacids like calcium carbonate.

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Ezetimibe Pharmacology

Ezetimibe Pharmacology

On this episode, I discuss ezetimibe pharmacology. Ezetimibe works by inhibiting Niemann-Pick C1-Like1 (NPC1L1) transporter. This transporter aids in cholesterol absorption so by blocking it, we can reduce cholesterol levels (and LDL) in the bloodstream.

Ezetimibe is usually very well tolerated. Diarrhea, myopathy, and elevations in LFT’s are adverse effects that have been reported but do not occur at high rates.

Ezetimibe is dosed at 10 mg once daily. This is a nice advantage because this is a starting dose and the usual treatment dose.

With the most recent cholesterol guideline updates, I do expect ezetimibe to be utilized a little more than it used to be. They place more emphasis on a target LDL and getting patients to goal.

Statins are going to be used first line for cholesterol and ezetimibe will be an add on therapy to consider. They don’t, unfortunately, lower cholesterol as much as high-intensity statins do.

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Azithromycin Pharmacology

Azithromycin Pharmacology

On this episode, I cover azithromycin pharmacology. This drug primarily acts by inhibiting protein synthesis. It binds to the 50s ribosomal subunit.

GI adverse effects like nausea and diarrhea are going to be the most common with azithromycin.

Azithromycin has been associated with prolonging the QT interval. Drugs like amiodarone, ondansetron, citalopram, antipsychotics, and quinolone antibiotics can also prolong the QT interval.

One major advantage that azithromycin has over other antibiotics is that it has a long half life which allows for once daily dosing.

Azithromycin has numerous uses like pneumonia, MAC, alternative for ear infections in patients with a beta-lactam allergy, certain STD’s, and also is rarely used in long term COPD exacerbation prevention.

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Rivaroxaban Pharmacology

Rivaroxaban is a factor 10a inhibitor that inhibits clot formation and thins the blood.

Rivaroxaban needs to be monitored for bleed risk. Checking periodic CBC can help us assess if hemoglobin and hematocrit are remaining stable.

Enzyme inducers like rifampin, St. John’s Wort, and carbamazepine can reduce concentrations and increase the risk of treatment failure.

NSAIDs and antiplatelet medications can significantly increase the risk of bleed with rivaroxaban.

Rivaroxaban should not be used with dual P-glycoprotein and CYP3A4 inhibitors. Examples include ketoconazole, itraconazole, and ritonavir.

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Valproate Pharmacology

Valproate Pharmacology

Valproate (valproic acid, Depakote) has numerous uses which includes migraines, seizures, and bipolar disorder.

In a patient who is taking valproate, it is important to monitor for signs and symptoms of confusion as this drug can cause elevated ammonia levels.

When switching between dosage forms of valproate, you must recognize that the bioavailability is not the same between each different dosage form. This could lead to toxicity or treatment failure.

Valproic acid has a boxed warning for hepatotoxicity and liver function needs to be monitored.

Valproic acid can increase lamotrigine levels which ultimately could lead to an increased risk of lamotrigine induced SJS.

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Donepezil Pharmacology

On this episode I discuss the pharmacology of donepezil.

Donepezil is an acetylcholinesterase inhibitor. In dementia, that is a deficiency in acetylcholine and donepezil helps preserve this neurotransmitter.

Donepezil can cause weight loss, GI upset, and diarrhea. This is an important monitoring parameter in our dementia patients.

There is the possibility for donepezil to cause bradycardia and insomnia. Keep an eye out for these adverse effects as they can and do happen in real practice.

Anticholinergics are notorious for blunting the effects of donepezil. We must look out for drug interactions from older anticholinergics like diphenhydramine, amitriptyline, and hydroxyzine.

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