Which formulation bypasses first-pass hepatic metabolism by absorbing directly through mucous membranes under the tongue?
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Clinical Pharmacology · Introduction to Pharmacology
Medication Forms and Formulations
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A drug's formulation is the physical form it's manufactured into — tablet, capsule, liquid, patch, injectable — chosen deliberately to control how fast and where the medication is absorbed. The same active ingredient can behave very differently depending on formulation, which is why altering a form (crushing a tablet, opening a capsule) can be dangerous. Nurses must recognize which forms are engineered for special release or protection so they don't accidentally destroy that design.
The college version
Solid Oral Forms
Tablets are compressed powder mixed with excipients — binders, fillers, disintegrants — that hold the tablet together and control breakdown. Plain tablets dissolve in the stomach, but specialized versions exist. Enteric-coated (EC) tablets have a polymer coating that resists stomach acid, dissolving only in the more alkaline small intestine, protecting either the stomach from an irritating drug (like aspirin) or the drug from acid degradation. Extended-release forms (ER, XR, SR, or CR) use a matrix or coating that releases drug slowly over many hours, allowing once- or twice-daily dosing instead of frequent doses. Sublingual tablets dissolve under the tongue, absorbing directly into systemic circulation through a rich blood supply and bypassing the stomach and liver first-pass metabolism — nitroglycerin is a classic example, valued for rapid onset. Capsules encase powder or liquid in a gelatin shell and may also carry coated beads formulated for extended release.
Why Crushing or Splitting Can Be Dangerous
Crushing an EC or ER tablet, or opening an ER capsule, destroys the mechanism controlling release location or rate. The entire dose can then be absorbed at once — dose dumping — risking toxicity, or the stomach is exposed to a drug meant to bypass it. As a rule, tablets marked EC, ER, XR, SR, or CR should never be crushed or split unless the manufacturer states the tablet is scored.
Liquid and Semisolid Forms
Solutions are drugs fully dissolved in a liquid vehicle, giving a uniform dose needing no shaking. Suspensions contain solid particles dispersed but not dissolved; they settle over time and must be shaken before dosing for accuracy. Elixirs are clear, sweetened, alcohol-containing solutions for drugs otherwise poorly soluble. Ointments are oil-based semisolids forming a protective barrier; creams are oil-in-water emulsions that absorb more easily, preferred for moist skin lesions.
Other Delivery Forms
Transdermal patches deliver a steady, controlled dose through the skin over hours or days, useful for stable blood levels while avoiding first-pass metabolism. Suppositories are solid forms inserted rectally or vaginally that melt at body temperature when oral dosing isn't possible. Aerosols and inhalers deliver drug as a fine mist or powder to the respiratory tract for rapid local action with minimal systemic exposure. Injectables are sterile solutions given by needle, offering the fastest onset since they bypass the GI tract and, with IV use, first-pass metabolism entirely.
The Role of Excipients
Every formulation contains excipients — binders, fillers, coatings, preservatives, flavorings — pharmacologically inactive but essential to stability and controlled release. Because excipients affect dissolution, products with an identical active ingredient but different excipients aren't always interchangeable.
Eli explains
The same idea, in plain words
Explain it like I’m 10
Think of medicine like candy wrapped in different ways. A regular tablet is candy you chew right away — fast. Some tablets have a hard shell (enteric coating) so they don't melt in your mouth, only later in your tummy, like candy built to survive a hot car and melt once it's somewhere cooler. Extended-release tablets are like a layered gummy that slowly releases flavor over hours instead of all at once. Crush that special candy and you break its layers, dumping all the flavor in one bite — for medicine, that "all at once" can make you sick. That's why you never crush or chew special-release tablets — you'd be breaking their built-in design.
Check yourself
2 review questions from the chapter. Try each one, then open the answer.
A patient with nausea and vomiting cannot reliably keep oral medication down and cannot tolerate an IV line. What non-oral, non-injectable formulation might be considered, and why does it work despite the GI upset?
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Suppository
A rectal or vaginal suppository melts at body temperature and absorbs through the mucous membranes there, so it doesn't need to be swallowed or stay down in an upset stomach, and it avoids needing a needle.
A patient tells you they've been splitting their "XR" blood pressure tablets in half to save money. What is your main clinical concern, and what should you tell them?
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Splitting an XR tablet can cause dose dumping
XR means extended-release, so splitting it destroys the mechanism spreading the dose over time, releasing too much drug too fast and risking a dangerous blood pressure drop. Tell the patient never to split it unless the label says it's scored, and to ask the pharmacist about cost-saving alternatives instead.
Quick check
3 questions here. Answers stay hidden until you check.
A nurse is about to give an oral suspension. What must be done immediately before measuring the dose, and why?
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What is the primary danger of crushing an extended-release (ER) tablet?
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