Memorizing Pharmacology Podcast: Prefixes, Suffixes, and Side Effects for Pharmacy and Nursing Pharmacology by Body System

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The body system we continue to cover is gastrointestinal and omeprazole, esomeprazole, lansoprazole, pantoprazole are all proton pump inhibitors PPIs. 

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Suffixes

Omeprazole (Prilosec) with the -prazole suffix, p-r-a-z-o-l-e suffix is a true proton pump inhibitor, abbreviated PPI. We want to watch out for aripiprazole (Abilify) and brexpiprazole (Rexulti) which are antipsychotics, not PPIs but have the -piprazole ending, p-i-p-r-a-z-o-l-e. Also, some drug cards say the ending is -azole, but that is not an actual suffix, that is a chemical group, using that ending might have you confuse antifungals like fluconazole (Diflucan) for PPIs, so again, the PPI suffix is -prazole.

You will notice that omeprazole (Prilosec) and esomeprazole (Nexium) are very similar and it’s that omeprazole contains two molecules, a left and right mirror image and esomeprazole only contains the left-handed image. In Latin, left is sinister, so the “es, e-s” represents that only left-handed side. Why does that matter? That left-handed molecule is the active molecule.

Mechanism of Action (MOA)

PPIs or “prazoles” work by blocking your stomach’s parietal cells which normally release hydrogen ions contributing to the stomachs’ acidity. This, without the proton pump inhibitor, could lead to heartburn or possible GI ulceration. The proton pump inhibitor blocks the hydrogen/potassium ATPase pump preventing protons from going in the stomach. This raises the pH, making it more basic, and removes the excessive acid.

Indications

We then use proton pump inhibitors to manage heartburn, gastroesophageal reflux disease (GERD), peptic ulcer disease, and Barrett's esophagus. Barrett’s esophagus is a condition where the acid reflux damages the esophagus causes it to redden. Many times patients who are on chronic NSAIDs or anticoagulants have a higher GI bleed risk and a proton pump inhibitor is for prophylaxis rather than active treatment.

Dosing

Traditional dosing is to give the PPI 30 to 60 minutes before breakfast. A concern comes when the medication does not seem to work, but it is not the medication, rather, the patient is taking with or even after breakfast. Make sure you know which is which. Also, H2 blockers work a bit more quickly, so the patient might expect a similar timetable with a PPI, let them know that it will take a bit longer.

Clinical Considerations

Acute use for a few weeks, especially with over-the-counter lengths of time, usually 2 weeks, tends to cause few side effects. Long term, however, we have concerns of B-12 deficiency, increased fracture risk, C. Diff, an opportunistic infection. Again, B-12 deficiency comes because the now less acidic stomach does not do as good a job at absorbing B-12.

Before we start this section, here’s a reminder contrasting enzyme inhibition and enzyme induction. A drug that inhibits and enzyme blocks the enzyme somewhat increasing drug levels making the patient toxic. A drug that induces and enzyme, makes the enzyme work better reducing drug levels and making the patient subtherapeutic.

CYP2C19 inhibition can happen with citalopram (Celexa) and escitalopram (Lexapro), so in this case the antidepressant drug levels can go up leading to QTc prolongation. That’s why we have dosing maximums on citalopram of 20 milligrams daily with someone on omeprazole.

CYP2C19 induction with omeprazole and clopidogrel (Plavix) is one class example as clopidogrel is a pro-drug and by inducing the enzyme to break down more clopidogrel, the enzyme lowers clopidogrel levels. A pro-drug is one that is not quite the drug yet, the liver may have to metabolize it into a drug. Clopidogrel itself is an antiplatelet drug, so reducing the effectiveness of an antiplatelet drug while trying to prevent myocardial infarction (heart attacks) and strokes.

Note, prescribers can use cilostazol (Pletal) for intermittent claudication, a problem with blood flow in the legs where they might be in pain for short distances and the drug allows them to walk further is also a concern. Using lansoprazole or a similar PPI might create a favorable effect.

Some drugs need an acidic environment for absorption like iron supplements and lowering the acidity runs counter to the best situation for iron. Adding ascorbic acid, vitamin C can help.

Cefuroxime (Ceftin) is a second-generation cephalosporin antibiotic with good gram-positive coverage, but one might change to another antibiotic if they see omeprazole in the chart.

Mesalamine (Pentasa) for ulcerative colitis and itraconazole (Sporanox) a...

The Classroom Cardio Lecture Part 1 of 3, you can complete the quizzes here https://residency.teachable.com/p/mobile

An overview of over-the-counter pharmacology Part 1, if you are looking for the book, you can find it here https://www.audible.com/pd/B09JVBHRXK/?source_code=AUDFPWS0223189MWT-BK-ACX0-281667&ref=acx_bty_BK_ACX0_281667_rh_us

The Classroom Cardio Lecture Part 2 of 3, you can complete the quizzes here https://residency.teachable.com/p/mobile

The Classroom Neuro/Psych Lecture Part 1 of 4, you can complete the quizzes here https://residency.teachable.com/p/mobile