Real Life Pharmacology - Pharmacology Education For Health Care Professionals

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

On this episode of the Real Life Pharmacology Podcast, I discuss cetirizine pharmacology. Cetirizine, commonly known as Zyrtec, is a 2nd generation antihistamine. Compared to 1st generation antihistamines, like diphenhydramine and chlorpheniramine, 2nd generation antihistamines have fewer anticholinergic effects. Pharmacologically, cetirizine works by selectively blocking histamine from binding to the H1 receptor. The uses for cetirizine are allergic rhinitis, itching, and sometimes acute allergic reactions. Commonly, cetirizine is dosed at 10 mg daily, and can even be escalated to 10 mg twice daily in rare situations. In adults 77 years old and older, the manufacturer recommended dose tops out at 5 mg daily. There are also liquid and chewable formulations for children.  The adverse drug reactions cetirizine are mostly dose-dependent and related to its pharmacology. Out of all of the 2nd generation antihistamines, like fexofenadine and loratadine, cetirizine is the most sedating. Other adverse drug rea

Folic acid is a water-soluble vitamin; compared to fat-soluble vitamins, accumulation is not as much of an issue. It is responsible for the formation of coenzymes, DNA synthesis, erythropoiesis, and certain metabolic processes. Due to the mechanism of folic acid, if there is a deficiency present, anemia can manifest. Although the recommended dietary intake is 0.2 mg, supplementation may be necessary. Some situations where supplementation may be desired are prevention of neural tube defects in pregnancy, patients suffering from alcohol abuse disorder, bariatric surgery patients, and certain types of GI disorders where malabsorption may be present. If a patient is taking certain medications folic acid supplementation may be necessary as well. Notable drugs where a patient may require folic acid include methotrexate and phenytoin.  The dosages used most often when supplementing folic acid are in the 1-5 mg range, and most of the time it will be 1 mg. Folic acid has a relatively safe adverse drug reaction prof

On this episode, I discuss insulin glargine pharmacology. Insulin glargine is a long-acting insulin that has the common brand names Lantus, Basaglar, and Toujeo. Due to the pharmacology of insulin glargine, it provides a baseline coverage of insulin. It cannot manage acute elevations in blood glucose like target-specific meals. Instead, insulin glargine is used to decrease blood sugar throughout the day.  It is normally dosed once a day, and sometimes a patient will have another type of insulin that’s rapid-acting, like Humalog. The daily insulin dose will vary, but it’s frequently a 50/50 split between long-acting, and rapid-acting. Dosing of insulin glargine in Type 2 diabetes is usually started at 10 units, but that can vary based on the patient or pertinent clinical data. Whenever doses need to be changed, it’s typically done in the range of 3-7 day intervals. Generally, when dose increases are desired, and the risk for hypoglycemia is low, a 10-20% increase is mostly what’s done. When converting betwe

On this episode, I discuss primidone pharmacology, adverse effects, and drug interactions. Primidone, or Mysoline, is an anticonvulsant most commonly used for essential tremors. The primary pharmacological mechanism of action of primidone is similar to other anticonvulsants, like phenobarbital. It causes a reduction in the activity of neurons. Both primidone and its metabolites are potent anticonvulsants. Primidone alters the transmembrane Na/Cl transport channel to reduce the frequency of nerve firing. Phenobarbital, one of primidone’s active metabolites, interacts with GABA-A receptors and chloride channels to reduce nerve excitability.    Typically B-blockers are used first for essential tremors, then primidone is the next option if B-blockers are ineffective. The dose of primidone can change depending on the use. At lower doses, around 250-700 mg/day (often lower doses than 250 mg will be used), it can indicate that it is being used for essential tremor. When it’s administered at higher doses, up t

I cover melatonin pharmacology on this episode of the Real Life Pharmacology Podcast. Melatonin, commonly taken by patients for insomnia, is an endogenous hormone produced by the pineal gland. It is an over-the-counter supplement available in dosage forms such as liquid drops, gummies, and tablets. The pharmacology of melatonin is primarily through the activation of melatonin receptors in the suprachiasmatic nucleus; it is also a derivative of L-tryptophan. The production and secretion of melatonin is stimulated by darkness and is inhibited by light. Melatonin concentrations are also shown to vary with age. Its production primarily begins between months 3-4 post-birth, and it peaks between years 1-3. The production and secretion decrease with age and can play a role in insomnia in adults. The doses of melatonin can vary but is commonly found in 1 mg, 3 mg, 5 mg, and 10 mg. Although it is usually taken in higher doses, doses between 0.1-0.5 mg may be adequate.  Certain things need to be taken into consi

Furosemide is a loop diuretic most commonly recognized by its brand name, Lasix. Pharmacologically, it acts by inhibiting the reabsorption of Na/Cl in the thick ascending limb of the loop of Henle. The inhibition of electrolyte reabsorption results in a loss of fluids causing diuresis. Since it has a diuretic effect, it is commonly used to treat congestive heart failure, general edema, ascites due to cirrhosis, and to aid in fluid elimination.  If a patient has a new prescription of furosemide, it’s important to look for drug-induced causes of edema. Common causes of drug-induced edema are the calcium-channel blockers (amlodipine, nifedipine, diltiazem, verapamil), some anticonvulsants (pregabalin, gabapentin), pioglitazone, and NSAIDs. In times when oral furosemide is not readily available, 40 mg of furosemide is equivalent to roughly 20 mg torsemide, or 1 mg bumetanide. If IV furosemide is desired and the patient is already on an oral formulation, generally, the approximate equivalent IV dose is 50% of t

Background: - Hydroxyzine Pharmacology Hydroxyzine, common brands Atarax, and Vistaril, is a first-generation antihistamine. It is a part of the piperazine drug class[1], sharing structural similarities to other antihistamines like Cetirizine, but also drugs of other classes like ranolazine, buspirone, clozapine. Being an H1 blocker, hydroxyzine is commonly used for itching, anxiety, analgesia, urticaria, and insomnia. The main adverse drug reactions associated with hydroxyzine are the anticholinergic effects common with most antihistamines, dry mouth, headache, urinary retention, QTC prolongation, drowsiness[2]. Interactions: Due to hydroxyzine’s pharmacology and mechanism of action, it can exacerbate or worsen gastroparesis by decreasing smooth muscle contraction in the GI tract, and has similar effects on benign prostatic hyperplasia by worsening urinary retention. Hydroxyzine is metabolized into its active drug, cetirizine, by CYP3A4 and CYP3A5[3]. As such, hydroxyzine’s efficacy can be increased with

On this episode, I cover clinical tips and practice pearls surrounding vitamin B12 pharmacology. Vitamin B12 deficiency plays a critical role in the development of macrocytic anemia. There are medications that you have to be aware that can deplete vitamin B12. Metformin, colchicine, and PPIs are some common examples. A lack of intrinsic factor can lead to B12 deficiency. Intrinsic factor is necessary for adequate GI absorption of vitamin B12.

On this episode, I discuss ketamine pharmacology. Ketamine is primarily broken down by CYP2B6 which fortunately does not have a lot of common medications that can interfere with its action. Ketamine can cause psychiatric type adverse effects such as hallucinations, nightmares, and vivid dreams. At lower to moderate dosages, ketamine does have some mild sympathetic activity which can raise blood pressure and heart rate.

On this episode of the Real Life Pharmacology Podcast, I cover topiramate pharmacology. Topiramate is indicated for migraine prevention, seizures, and weight loss which are the most common uses that I see this medication used for. Topiramate has carbonic anhydrase activity, so rarely, use of this drug may induce metabolic acidosis. By far, the most common patient complaint I get with the use of topiramate is that it causes cognitive slowing or impairment.

On this episode I discuss colchicine pharmacology, adverse effects, drug interactions, and pharmacokinetics. Colchicine ultimately works by reducing the activity of neutrophils that help contribute to pain and inflammation associated with gout. Colchicine does have some drug interactions with medications and grapefruit juice via CYP3A4. The most common dose limiting side effect of colchicine is diarrhea. Colchicine can be used as a potential alternative to NSAIDs or corticosteroids in the management of a gout flare.

Fexofenadine is a 2nd generation antihistamine that is primarily used for allergic rhinitis. I cover fexofenadine pharmacology on this podcast episode. Fruit juices can actually impair the absorption of fexofenadine and increase the risk of treatment failure. Fexofenadine is mildly anticholinergic but overall has low to no CNS penetration. Because fexofenadine has low CNS penetration, the risk for sedation and dizziness is much lower than older antihistamines like diphenhydramine.

On this episode I discuss empagliflozin pharmacology and how this medication lowers blood sugar. In this episode, I talk about empagliflozin pharmacology. Empagliflozin is more commonly known by the brand name Jardiance and is in the class of sodium-glucose co-transporter-2 inhibitors or SGLT2 inhibitors. Jardiance use has definitely escalated over the last few years in the management of type 2 diabetes, but this has been changing a little bit as well due to recent evidence for the cardiovascular benefits from this medication. The sodium-glucose co-transporter-2 is found in the kidney and is responsible for helping the body reabsorb glucose back into the bloodstream. The way empagliflozin works is by inhibiting this transporter, more glucose is excreted into the urine and ultimately lowering the blood sugar since it is not being reabsorbed. Empagliflozin has additional benefits outside of blood sugar reductions. Studies found that patients with or without diabetes receive cardiovascular protective effec

On this episode, I discuss rifaximin pharmacology. Rifaximin is most commonly used in hepatic encephalopathy and C. difficile infection. Rifaximin systemic absorption is minimal so that is why it is primarily only used for GI conditions. Drug interactions with rifaximin are fairly minimal compared to its cousin rifampin which has tons of drug interactions.

On this episode of the Real Life Pharmacology Podcast, I discuss naproxen pharmacology. Naproxen can raise the concentrations of lithium and increase the risk for toxicity. Compared to most other NSAIDs, naproxen tends to have a lower cardiovascular risk. Naproxen can contribute to renal insufficiency, GI bleed risk, and CHF exacerbations.

On this episode, I discuss cyclosporine pharmacology. This medication is an immunosuppressant used to reduce the risk of transplant rejection. Cyclosporine has a long list of potential adverse effects such as hyperglycemia, renal impairment, GI toxicity, and hypertriglyceridemia. Important monitoring parameters for cyclosporine include drug levels, electrolytes, renal function, and blood sugars. CYP3A4 interactions are critical with cyclosporine. Inhibitors can raise concentrations and inducers can lower concentrations.

On this episode, I discuss leflunomide pharmacology. It is classified as a DMARD and is primarily used in rheumatoid arthritis. Leflunomide carries a boxed warning for hepatoxicity. LFTs must be monitored with its use. Leflunomide can inhibit CYP2C8 which plays an important role in pioglitazone metabolism. Concentrations of pioglitazone can go up on account of this interaction. TB screening should be done prior to beginning the immunosuppressant leflunomide.

Baclofen is primarily used for its ability to help relieve muscle spasms. I discuss baclofen pharmacology on this podcast episode. Baclofen should not be abruptly discontinued as it can cause a significant withdrawal reaction whose symptoms may include fever, spasticity, rhabdomyolysis, and death. While baclofen generally avoids any issues with CYP enzyme interactions, it is eliminated by the kidney. Renal function changes can alter drug concentrations. Sedation, confusion, dizziness, hypotension, and GI upset are some of the more common adverse effects of baclofen.

On this episode, I discuss bromocriptine pharmacology. It is a dopamine agonist that can be used for hyperprolactinemia and Parkinson's symptoms. One of the major side effects of bromocriptine is nausea which stems from its dopamine agonist action. Because bromocriptine is a dopamine agonist, it can counteract the action of antipsychotics. Bromocriptine is broken down by CYP3A4, so drug interactions can be common. Erythromycin, some of the azole antifungals, verapamil, grapefruit juice, and diltiazem are all medications that can increase concentrations.