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Memory Pharm

Beta-1 Cardioselective Beta-Blockers

โค๏ธ Cardioselective beta-blockers work on the beta-1 receptors. Beta-1 receptors primarily are found in cardiac tissues whereas beta-2 receptors are located in the lungs (remember: 1 heart, two lungs). โ  โ  โค๏ธ Cardioselective beta-blockers exert their effect by binding to the beta-1 receptor sites selectively and inhibiting the action of epinephrine and norepinephrine on these sites. They are often preferred in patients with respiratory disease as they are less likely to cause constriction of airways or peripheral vasculature.โ 

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Calcium Channel Blockers

Calcium channel blockers (CCBs) are used in the treatment of many cardiovascular conditions including hypertension and angina. They are divided into subclasses, non-dihydropyridines and dihydropyridines and differ by their pharmacokinetic properties, clinical uses, response, and selectivity.

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Key Points

The non-dihydropyridine CCBs do not end in the suffix โ€˜-ineโ€™ hinted by the name of the subclass, non-dihydropyridines. They cause more cardiac depression and less vasodilation than dihydropyridine CCBs resulting in a reduction in heart rate and cardiac contractility.

  • Verapamil
  • Diltiazem

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Dihydropyridine CCBs end in the suffix โ€˜-ineโ€™ and have more vascular selectivity and fewer cardiac effects. They act primarily as peripheral vasodilators and are used in the treatment of hypertension and angina. They do not suppress AV node conduction or SA node automaticity.

  • Amlodipine
  • Nicardipine
  • Nifedipine
  • Nimodipine
  • Felodipine

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Mechanism of Action:

The name of this class, calcium channel blockers, hints at its mechanism of action – inhibits the entry of calcium into cells of the cardiac and peripheral vascular smooth muscles.ย 

  • Calcium entry into L-type channels of cardiac and peripheral vascular cells is needed for them to contract or constrict more strongly.ย 
  • By blocking calcium entry, calcium channel blockers causeย 
    • peripheral vascular smooth muscle relaxation (decreases blood pressure)
    • decreased myocardial contractility (decrease myocardial demand making them effective in angina)
    • decrease heart rate and conduction velocity (useful in arrhythmias).ย 

Indications:

Non-dihydropyridinesย 

  • Hypertension
  • Arrhythmias

Dihydropyridines

  • Hypertension
  • Angina
  • Migraines

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Side Effects:ย 

The main side effects of calcium channel blockers are hypotension and dizziness which is related to their effects on vasodilation so it is easier for you to memorize.ย 

In addition, they can also cause the following side effects by subclass:

  • Non-dihydropyridines
    • Constipation, gingival hyperplasia, worsening cardiac output, and bradycardia.
  • Dihydropyridines
    • Peripheral edema, headache, flushing

Clinical Pearls/Education:

  • Non-dihydropyridines are contraindicated in patients with decompensated heart failure, second or third-degree AV blockade, and sick sinus syndrome due to their inhibitory effects on the SA and AV node, slowing cardiac conduction and contractility.ย 
  • Monitor patients for hypotension, edema, and bradycardia.ย 
  • Peripheral edema is dose-dependent and may occur within 2 to 3 weeks of initiating calcium channel blocker therapy, particularly dihydropyridines. Peripheral edema due to the redistribution of fluid from the intravascular space to the interstitium.ย 
  • Diphydroyridines can cause reflex tachycardia and acute hypotension due to their potent vasodilating effects. This effect is more common with first-generation short-acting dihydropyridines (e.g. immediate-release nifedipine) and less with newer agents that are longer acting (e.g. amlodipine). The effect may be lessened by using sustained-release formulations.
  • Diltiazem decreases AV node conduction and heart rate to a lesser extent than verapamil but these drugs should be monitored closely for bradycardia especially with patients on beta-blockers.ย 
  • Verapamil and diltiazem are considered moderate cytochrome P450 3A4 enzyme inhibitors and should be monitored for drug interactions.ย 
  • Constipation is a more common side effect with verapamil and occurs to a lesser extent with diltiazem.ย 

References:

  • McKeever RG, Hamilton RJ. Calcium Channel Blockers. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482473/
  • Maclaughlin EJ, Saseen JJ. Hypertension. In: DiPiro JT, Yee GC, Posey L, Haines ST, Nolin TD, Ellingrod V. eds. Pharmacotherapy: A Pathophysiologic Approach, 11e. McGraw-Hill.

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Calcium Channel Blockers (Mechanism of Action)

๐Ÿ’Š Calcium channel blockers (CCBs) are used in the treatment of many cardiovascular conditions including hypertension and angina. They are divided into subclasses, non-dihydropyridines, and dihydropyridines and differ by their pharmacokinetic properties, clinical uses, response, and selectivity. โ  โ  ๐Ÿ’Š The name of this class, calcium channel blockers, hints at its mechanism of action โ€“ inhibits the entry of calcium into cells of the cardiac and peripheral vascular smooth muscles. โ  โ  ๐Ÿ—’๏ธ Calcium entry into L-type channels of cardiac and peripheral vascular cells is needed for them to contract or constrict more strongly. โ  โ  ๐Ÿ—’๏ธ By blocking calcium entry, calcium channel blockers cause:โ  ๐Ÿ‘‰๐Ÿป peripheral vascular smooth muscle relaxation (decreases blood pressure)โ  ๐Ÿ‘‰๐Ÿป decreased myocardial contractility (decrease myocardial demand making them effective in angina)โ  ๐Ÿ‘‰๐Ÿป decrease heart rate and conduction velocity (useful in arrhythmias). โ 

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Cholinergic Muscarinic Agonist Effects

๐Ÿ‘‰๐Ÿป Cholinergic muscarinic agonists are drugs that bind to and activate muscarinic cholinergic receptors and increase the activity of the parasympathetic nervous system. They are most commonly used when it is desirable to increase smooth muscle tone, especially in the GI tract, urinary bladder, and eye. They may also be used to reduce heart rate. โ  โ  ๐Ÿ‘‰๐Ÿป Direct cholinergic agonists work by resisting acetylcholinesterase, thus preventing its breakdown. Drugs in this class include bethanechol, carbachol, and methacholine, and pilocarpine.โ  โ  ๐Ÿ‘‰๐Ÿป Indirect cholinergic agonists work by inhibiting the acetylcholinesterase enzyme preventing the degradation of acetylcholine. Drugs in this class include neostigmine, physostigmine, galantamine, donepezil, and rivastigmine. โ 

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CYP450 Enzymes, Major Inducers of

๐Ÿ‘‰๐Ÿป Drugs that are inducers increase CYP450 enzyme activity by increasing enzyme synthesis. โ  โ  ๐Ÿ‘‰๐Ÿป A drug also may be metabolized by the same CYP450 enzyme that it induces. Carbamazepine (Tegretol), a potent enzyme inducer, must be initiated at a low dose and then increased at weekly intervals as its half-life gradually decreases over time.โ 

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CYP450 Enzymes, Major Inhibitors of

The CYP450 enzymes are essential for the production of numerous agents including cholesterol and steroids. Additionally, these enzymes are necessary for the detoxification of foreign chemicals and the metabolism of drugs.โ  โ  Drugs that are CYP450 inhibitors block the metabolic activity of one or more of the CYP450 enzymes. The extent to which an inhibitor affects the metabolism of a drug depends upon factors such as the dose and the ability of the inhibitor to bind to the enzyme.โ 

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Drug Allergies

While any drug can cause an allergic reaction, letโ€™s focus on the top 3 most common drug allergies:โ โ €
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๐Ÿ’Š Penicillin allergiesโ โ €
๐Ÿ’Š Sulfa allergiesโ โ €
๐Ÿ’Š Opioid allergiesโ โ €
โ โ €
When you realize a patient has an allergy to a medication you are about to prescribe, verify, or administer, always assess to see if the patient is TRULY allergic to the medication by:โ โ €
โ โ €
โœ๏ธ Asking what reaction they had to itโ โ €
โœ๏ธ Determine if the reaction is a considered side effect/intolerance vs. a true allergy that is IgE mediated (anaphylaxis or angioedema) โ โ €
โœ๏ธ If it is a true allergy, replace the medication with an alternative drugโ โ €
โœ๏ธ If using another agent that could potentially cross-react be sure to monitor the patient closely โ โ €
โ โ €
Most often patients who report they have an allergy to one of these medications are truly not allergic to it but are often just intolerant to its side effects which can lead to costlier and less effective medications being used in its place. โ Itโ€™s important to assess the nature of the allergy and weigh the risks and benefits of using other alternatives.

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Drug Antidotesโ  #1โ €

๐Ÿšฆ Antidotes are substances used to reverse the effects of poisoning. The word “antidote” itself derives from the Greek word, antidoton, meaning “administered as a remedy’.โ โ €
โ โ €
Some antidotes are used to treat one specific drug while other antidotes (ex: charcoal) can reverse the effects of many different toxins. โ โ €

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Drug Names #1

There are a plethora of drug facts to memorize for school, but it is definitely helpful when their names hint at what they are used for, their mechanism of action, frequency, or duration. โ  ๐Ÿ’Š Lasix: short for ‘last six hours’ because of the 6-hour duration of action. Try not to administer this diuretic to patients after 4 pm to decrease nighttime awakenings.โ  โ  ๐Ÿ’Š Macrobid: this formulation of Macrodantin is given BID (twice a day). Macrodantin is recommended to be given 4 times a day. Ensure you are using the right formulation for the right frequency. โ  โ  ๐Ÿ’Š Protonix: Protonix belongs to a class of proton pump inhibitors. Its brand name, Protonix, tells you that it is used to ‘nix protons’ or acid and is used to treat GERD and acid-reflux disorders. โ  โ  ๐Ÿ’Š Lopressor: brand name for metoprolol, a beta-blocker that is used for high blood pressure. The brand name, lo-pressor, tells you that it is used to help ‘lower pressures’. โ  โ  ๐Ÿ’Š Flonase: brand name for fluticasone nasal spray. Its name, Flonase, sounds an awful lot like ‘flow nasal’ which tells you that it is used to treat allergies that commonly cause nasal congestion. โ  ๐Ÿ’Š Ambien: AM is the sig for morning and Bien means good in Spanish. It is a sleeping aid medication that translates into ‘good morning’. โ 

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Drug Names #2

Part 2 of It’s all in the name! Hope these mnemonics make it easier for you to memorize these medications. โ  ๐Ÿ’Š Flomax: brand name for tamsulosin, a medication used to treat urinary retention or benign prostatic hyperplasia (BPH). Its name tells you that it is used to ‘maximize flow’. โ  โ  ๐Ÿ’Š Lunesta: a sleep aid medication whose root word Luna means moon in Latin. โ  โ  ๐Ÿ’Š Xarelto: brand name for rivaroxaban, an oral anticoagulant. Its name hints at its mechanism of action, inhibiting factor Xa in the clotting cascade. โ  โ  ๐Ÿ’Š Fosamax: brand name for alendronic acid, it is a medication used to treat osteoporosis or bone weakening. Its name means os = bone, and max = great in Latin. โ  โ  ๐Ÿ’Š Prevacid: brand name for lansoprazole, it belongs to a class of proton pump inhibitors. Its name tells you that it ‘prevents acid’ and is used to treat GERD and acid-reflux disorders. โ  โ  ๐Ÿ’Š Glucophage: brand name for metformin. It is a medication used to treat type 2 diabetes. Its name derives from the Greek words gluco= glucose and phage = eat or consume. โ This helps you remember metformin’s mechanism of action is to increase uptake of glucose by cells in the body to be used as energy (or in other words increase insulin sensitivity). โ 

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Drug Names #3

๐Ÿ’Š Vicodin is the brand name for hydrocodone/acetaminophen. Its component hydrocodone is approximately 6 times (VI) times as potent as codeine (codin). โ  โ  ๐Ÿ’Š Levitra is the brand name for vardenafil, a medication used to treat erectile dysfunction. The article ‘Le’ is used to describe masculine nouns in French (‘La’ is used with feminine nouns) and vitra is similar to the word vitality. So together, the name masculine vitality will help you remember the indication for Levitra. โ  โ  ๐Ÿ’Š Actigall is the brand name for ursodiol, a medication used to dissolve certain types of gallstones. It sounds a lot like “ACTS ON THE GAL-bladder” to help you remember what it is used for. โ 

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Drug Names #5

๐Ÿ’Š Cisplatin is a chemotherapy medication used to treat a number of different cancers. Its name tells you that it is an isomer of a platinum-containing compound. โ  โ  ๐Ÿ’Š Maalox is used to treat heartburn, acid indigestion, sour stomach, and upset stomach. The name is an acronym that refers to the solution’s compositional elements: MAgnesium and ALuminum Oxide.โ  โ  ๐Ÿ’Š Sonata is the brand name of Zaleplon, a sedative used to treat insomnia. The prefix Sona means ‘sleepy’ in Portuguese to help you remember its indication. โ 

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