Pharmacology is one of the most challenge topics you will encounter as a healthcare professional, but it can be the most rewarding with a good understanding. Whether you are preparing to be a nurse, physician, physician assistant, pharmacist, dentist, nurse practitioner, pharmacy technician, pharmacologist, or other healthcare professional, this podcast will help you better understand pharmacology. In addition to giving you the basics like mechanism of action, side effects, drug interactions, etc., you will also be exposed to how medications actually impact patients in real life. In the Real Life Pharmacology podcast, Eric Christianson, PharmD shares his real world experiences about how a medication's mechanism of action, pharmacokinetics, adverse effects, and drug interactions can actually impact patients in both a positive and a potentially negative way. Eric Christianson PharmD is the author of the popular clinical pharmacy blog Meded101.com. People who are passionate about nursing, medicine, or pharmacy will find this podcast beneficial in helping them prepare for passing exams. This podcast is for educational purposes only and is not medical advice or intended to be a substitute for medical advice. Please seek advice from your pharmacist or primary care provider if you have questions about medications that you are taking.
On this episode, I discuss the pharmacology of zaleplon including side effects, drug interactions, and important clinical pearls.
On this episode, I breakdown the pharmacology of hydrochlorothiazide including adverse effects, drug interactions, and other clinical pearls.
On this episode, I discuss torsemide pharmacology, adverse effects, drug interactions and pharmacokinetics. Torsemide is commonly known as Demadex. It is a loop diuretic, and like other loop diuretics, it acts by inhibiting the reabsorption of Na+ and Cl- in the ascending loop of Henle. What results is a decrease in the reabsorption of water, causing a loss of electrolytes as well as water. The pharmacology of torsemide makes it useful in cases of heart failure, cirrhosis, or hypertension. Torsemide, and other loop diuretics, can also be a part of the prescribing cascade. For example, pregabalin and gabapentin, along with amlodipine and pioglitazone can cause or worsen edema, resulting in a new prescription of torsemide.
Torsemide is typically initially dosed between 5-20 mg, depending on the use. If the indication isn’t very severe it might be dosed lower, between 5-10 mg, or higher if it’s a more severe indication starting at 20 mg and titrated up. It should be cautioned in patients with a history of dehydration and renal failure, and it is contraindicated in cases of anuria, hepatic coma, and hypersensitivity. It may sometimes be necessary to be converted to furosemide or bumetanide, or torsemide from the other two. The conversion is, 20 mg of torsemide is equivalent to 40 mg of oral furosemide, which is equivalent to 1 mg bumetanide.
The adverse effects go hand-in-hand with its pharmacology, these include dehydration, increased urination, increased risk of acute renal failure, electrolyte imbalances, and ototoxicity. Also related to the pharmacology of torsemide, electrolytes, renal function, as well as blood pressure should be monitored. Kinetics may vary depending on what loop diuretic it is. It is generally more consistent with furosemide, but torsemide can sometimes have less variability as well as a longer half-life in comparison.
For drug-drug interactions, additive effects are the main concern. When combined with Sinemet or PDE inhibitors, there may be an unsafe drop in blood pressure. If it’s combined with SGLT2 inhibitors there can be increased diuresis. There can also be an increased risk of renal issues when taken with an NSAID, ACE inhibitors, or ARBs; if an NSAID is necessary, the dose or duration should be limited, and the kidney function should be monitored. The risk for ototoxicity increases when taken with aminoglycosides, and drugs that can cause edema should be monitored.
The main signs and symptoms of intolerance, or overdose, are extensions of its adverse effects and are related to its pharmacology. Commonly, it will be dehydration, hypotension, or symptoms of either. When treating overdoses, symptomatic relief is necessary; it is commonly achieved by fluid and electrolyte replacement.
In the podcast this week, I talk about doxylamine pharmacology. Doxylamine is a first-generation antihistamine; it is commonly an active ingredient in night-time medications like Unisom, Nyquil, and Mucinex. The pharmacology of doxylamine is similar to other first-generation antihistamines, it competitively inhibits the binding of histamine at H1 receptors. Its main uses are as sleep aides, in cough-and-cold medications, but doxylamine has also been given with pyridoxine to treat nausea and vomiting during pregnancy.
Doxylamine’s adverse reactions are related to its anticholinergic properties, they include dry eyes, dry mouth, increased fall risk, sedation, urinary retention, constipation, and confusion. Contraindications include concurrent use with a monoamine oxidase inhibitor, known hypersensitivities, concomitant alcohol use, and if the patient has the following conditions: elevated intraocular pressure, narrow-angle glaucoma, asthma, peptic ulcer disease, urinary bladder neck obstruction, or gastric outlet obstruction. It is also a Beer’s list drug due to its anticholinergic effects. The normal dose in adults is 25 mg. In cases of overdosage, the most common manifestation is exacerbations of its anticholinergic effects. The major complications of an overdose include arrhythmia, respiratory failure, seizures, hyperthermia, rhabdomyolysis, and coma.
When you know a patient is taking doxylamine, it’s important to be cognizant of their occupation, as well as what other conditions they may have. For example, doxylamine should be used with caution in patients that drive heavy machinery due to its sedating properties. You might be able to tell if a patient’s experiencing an adverse reaction exacerbation if they begin having worsening dementia symptoms or increased urinary retention. Other indications include the use of artificial tears, or saliva, or increased complaints of constipation. To monitor for doxylamine, it’s important to monitor the patient’s tolerability. The onset of doxylamine is relatively quick as well, with a peak concentration within 2-4 hours.
For drug-drug interactions, CYP interactions aren’t as concerning as usual. The main interaction to consider when a patient is taking doxylamine is additive anticholinergic effects. Sedative effects can increase when benzodiazepines, skeletal muscle relaxants, opioids, or antihistamines are concurrently taken. Doxylamine can also counteract the usefulness of dementia or BPH medications due to its anticholinergic properties. There is also a risk of increased anticholinergic burden when taken with skeletal muscle relaxants or tricyclic antidepressants.
Show notes provided by Chong Yol G Kim, PharmD Student.
Sacubitril Valsartan Pharmacology
On this episode, I breakdown the sacubitril valsartan pharmacology.
The drug for this week is the combination drug sacubitril/valsartan, also known as Entresto. Entresto has a novel dual mechanism of action to treat HFrEF. Sacubitril, currently, is the only FDA-approved medication that is a neprilysin inhibitor. For background, neprilysin is an enzyme that breaks down natriuretic peptides. The inhibition of neprilysin results in an increase in natriuretic peptides, which causes vasodilation, fluid loss, and a decrease in blood pressure. Valsartan is an angiotensin II receptor blocker; it prevents angiotensin II from binding to AT1 to reduce blood pressure by reducing vasoconstriction, synthesis, and release of aldosterone and ADH, cardiac remodeling, and renal reabsorption of sodium. The unique pharmacology of Entresto makes it advantageous to use in HFrEF and is even now one of the preferred agents.
Common adverse reactions that occur when taking Entresto are related to its dual mechanism pharmacology. The most common adverse reactions of Entresto are hyperkalemia, angioedema, hypotension, and renal impairment. Entresto is contraindicated in pregnancy due to fetotoxicity; it requires a 36 hour washout period when transitioning from an ACE inhibitor due to the increased risk of angioedema.
Entresto is initially dosed at 24/26 mg twice a day if the patient is on a low dose ACE inhibitor/ARB, or if the patient has not taken anything. If a patient is taking over 10 mg of enalapril equivalents a day or 160 mg of valsartan equivalents a day, then the preferred initial dose is 49/51 mg twice a day. Regardless of initial dosing, the target dose is 97/103 mg twice a day. In cases of severe renal impairment, or moderate hepatic impairment, the initial dosing should start at 24/26 twice a day; titration remains the same.
The pharmacology of Entresto leaves room for many potential drug-drug interactions. There’s a risk of duplicate therapy with other ACE inhibitors or ARBs. An exacerbation of adverse drug reactions can also occur when taking medications that can lower blood pressure, like Sinemet, or medications that can increase the risk for hyperkalemia, like trimethoprim, and spironolactone, or medications that can increase the risk of renal impairment, like NSAIDs. Entresto has also been shown to increase the risk of lithium toxicity.
Show notes provided by Chong Yol G Kim, PharmD Student.
Glipizide, or Glucotrol, is a sulfonylurea used for the treatment of Type 2 Diabetes. Pharmacologically, glipizide acts by stimulating beta-cells in the pancreas to release insulin. Specifically, glipizide will block the opening of ATP-sensitive potassium channels on the plasma membrane of beta-cells on the pancreas. The result of that is depolarization, which then causes stimulation of voltage-sensitive calcium channels, eventually causing the exocytosis of insulin. The increased insulin will then promote the storage of glucose, decreasing the amount of glucose in the blood.
Due to the pharmacology of glipizide, the concerning adverse drug reactions are hypoglycemia and weight gain. Other adverse drug reactions include diaphoresis, dizziness, syncope, nervousness, anxiety, tremors, and diarrhea. The contraindications include hypersensitivity, Type 1 Diabetes, and DKA. Glipizide is not used as often due to the risk of hypoglycemia and weight gain. Glipizide is usually dosed once daily, but it can be split up if the dose is escalated. There are differences in administration depending on the formulation. For immediate release formulations, glipizide should be taken 30 minutes before meals to ensure that absorption is stable. For extended formulations, it can be given with breakfast or any other meal.
Of all the sulfonylureas, glipizide is preferred in CKD. Other sulfonylureas, like glyburide, are not preferred due to a decrease in elimination that can result in dose accumulation. In geriatric populations, dosing is less aggressive to lessen the risk of any adverse drug reactions and more specifically hypoglycemia. There’s a risk of cross-reactivity with sulfonamide allergies, but the risk will vary and is low risk. If SJS occurs due to a sulfonamide-containing drug, glipizide likely wouldn’t be recommended.
The drug-drug interactions of glipizide include medications that can increase the risk of hypoglycemia, for example, medications like quinolone antibiotics and B-blockers can mask the symptoms of hypoglycemia. Other interactions include the type where it can counteract the effect of glipizide, for example, medications that can increase blood glucose levels like corticosteroids, antipsychotics such as olanzapine and clozapine, stimulants, and transplant medications like cyclosporine and tacrolimus. There are also CYP interactions that can impact glipizide since it’s metabolized by CYP2C9. More monitoring is warranted when medications that can inhibit CYP2C9, like fluconazole, and medications that can induce CYP2C9, like rifampin, are also given. In cases of overdose, hypoglycemia is most likely to occur. Correction of decreased glucose levels is necessary.
Show notes provided by Chong Yol G Kim, PharmD Student.
This is a great podcast. Eric provides accurate information and does so in a very plain spoken, easy to understand way. I appreciate all the work he puts into this, as well as the free resources that he offers.
This is a great podcast for newly graduate pharmacists because it provides a simple and brief reminder of specific drugs. Really impressed! Thank you
Great for pharmacy students!
I listen to one every day and it really helps me to understand and remember the meds.