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Dosage forms describe the physical preparation and routes describe how it enters the body. Both are definitional knowledge that supports Sig interpretation and calculation questions.
One of the easier parts of the largest domain, and worth securing early because other things depend on it.
Forms
Solid, liquid, semi-solid and gaseous preparations: tablets, capsules, solutions, suspensions, emulsions, ointments, creams, gels, suppositories, inhalers, patches, injectables.
The distinctions that matter are functional. A solution is dissolved and a suspension is not, which is why one is shaken and the other is not. One is local, one is systemic.
Routes
| Route | Means |
|---|---|
| Oral, PO | By mouth, swallowed |
| Sublingual, SL | Under the tongue |
| Topical | Applied to the skin for local effect |
| Transdermal | Through the skin for systemic effect |
| Rectal, PR | Rectally |
| Intravenous, IV | Into a vein |
| Intramuscular, IM | Into muscle |
| Subcutaneous, SC or SubQ | Under the skin |
| Inhalation | Into the lungs |
| Ophthalmic and otic | Eye and ear |
Topical acts where it is applied. Transdermal passes through the skin to act systemically. A patch delivering a drug to the whole body is transdermal even though you put it on the skin, and this pair is a routine distractor.
Why it supports other areas
Sig codes encode routes, so reading a Sig requires them. Calculation questions specify a form, and whether something is a solution or a suspension changes how a concentration behaves. Learn it as definitions.
Ophthalmic and otic are also a patient safety matter, since an ear preparation in an eye is a recognized error type.
Duration of therapy
Grouped with strengths and forms in the outline. It connects directly to days supply, which is a calculation question rather than a pharmacology one. Cheap marks.
How to study it
As definitions, in one or two sessions. It is finite, it does not change, and it is among the cheapest marks in the domain.
Common questions
What is the difference between a dosage form and a route?
The form is the physical preparation; the route is how it enters the body.
What is the difference between topical and transdermal?
Topical acts where applied; transdermal passes through the skin to act systemically.
What is the difference between a solution and a suspension?
A solution is dissolved; a suspension is not, which is why it is shaken.
Why does this area matter elsewhere?
Sig codes encode routes, and calculations specify forms.
How should I study it?
As definitions, in one or two sessions. It is finite and cheap to secure.