Chapter 7 Routes of Drug Administration

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Buccal and Sublingual (SL)

Some drugs are taken as smaller tablets which are held in the mouth or under the tongue. These are buccal or sublingual dosage forms. Buccal tablets are often harder tablets [4 hour disintegration time], designed to dissolve slowly. Nitroglycerin, as a softer sublingual tablet [2 min disintegration time], may be used for the rapid relief of angina. This ROA is also used for some steroids such as testosterone and oxytocin. Nicotine containing chewing gum may be used for cigarette smoking replacement.

Advantages:

First pass - The liver is by-passed thus there is no loss of drug by first pass effect for buccal or sublingual administration. Bioavailability is higher.

Rapid absorption - Because of the good blood supply to the area of absorption is usually quite rapid, especially for drugs with good lipid solubility.

Drug stability - pH in mouth relatively neutral (cf. stomach - acidic). Thus a drug may be more stable.

Disadvantages:

Holding the dose in the mouth is inconvenient. If any part of the dose is swallowed that portion must be treated as an oral dose and subject to first pass metabolism.

Usually more suitable for drugs with small doses.

Drug taste may need to be masked.

Figure 7.3.1 Typical Plot of Cp versus Time after Buccal Administration

Figure 7.3.2 Typical Plot of Cp versus Time after Sublingual Administration

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