IV Route Advantages — MFDS Part 1 MCQ

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EasyPharmacologyIV Route AdvantagesMFDS Part 1

During management of a medical emergency in a dental setting, assume that each listed route is available and clinically appropriate for the drug. Which route generally provides the most rapid and predictable systemic onset of action?

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Correct answer: D — Intravenous

The correct answer is **A. Intravenous**. Intravenous administration delivers the drug directly into the systemic circulation, avoiding an absorption phase and providing complete bioavailability. This generally gives the fastest and most predictable onset. The UK SmPC for intravenous lidocaine reports 100% bioavailability and therapeutic plasma concentrations within 1–2 minutes; comparative SmPC data for ketamine also show faster onset intravenously than intramuscularly. Intramuscular absorption depends partly on tissue perfusion. Oral drugs require gastrointestinal absorption and may undergo first-pass metabolism. Sublingual administration can be rapid but still requires mucosal absorption and is formulation-dependent. Rectal absorption is comparatively variable. In an actual dental emergency, the route must still follow the indication-specific UK emergency protocol.

Reference: Electronic Medicines Compendium. Lidocaine Injection BP 2% w/v, Summary of Product Characteristics, section 5.2 Pharmacokinetic properties. Revised 7 July 2025. https://www.medicines.org.uk/emc/product/15150/smpc