Pharmacokinetics of oral cavity

2. • Absorption
– Absorption of drugs is at rapid rate because
• Vascularity of oral cavity + thin epithelial linings
– For systemic drugs – this effect is desirable
• Eg. nitroglycerine
– For oral topical agents – to be retained in the oral cavity for as
long as possible. + rapid oral absorption can lead to toxicity and
significant reduction of drug effect in oral cavity
– Most drugs used to restrain plaque levels are highly ionized and
generally unable to penetrate the oral mucosa.

3. • Distribution
– When an agent is topically applied to oral cavity,
• Free drug will bind to the primary intended site – (bacteria in plaque)
• And can also distribute to other compartments (enamel, dentin, cementum
of tooth, oral mucosa, salivary proteins)
• Depending on concentrations, amount of exposed time, and chemical
nature of the drug used.
• Metabolism
– Sites of metabolism in oral cavity – mucosal epithelial cells, microorganisms,
enzymes found in saliva (quantitively small %)
– After swallowing – renal and hepatic tissues

4. • Clearance from oral cavity
– Main factor that determines drug clearance – saliva flow
– That rate of clearance is of profound importance in determining the duration of
time a drug is in contact with the tooth surface.
• Substantivity *
• The time that a drug is in contact with a particular substrate in the oral cavity
is defined as “substantivity”.
• Drugs with prolonged duration of contact – “high substantivity”
• Depends on 2 factors
• Degree of reversible, non specific binding to oral reservoirs
• Rate of clearance by salivary flow.

5. • Safety
• Efficacy
• Specificity (affects only on pathogenic bacteria)
• Substantivity
• No induced drug resistance
• Acceptable taste
• Low cost

6. • Kidd, E.A.M (2005). Essentials of Dental Caries . 3rd ed.
Oxford: Oxford University Press. 110-123.
• Thikkurissy, Sarat. (2011). Anticaries agents. In: Yagiela,
Dowd, Johnson, Mariotti, Neidle Pharmacology and
Therapeutics for Dentistry. 6th ed. United States: Elsevier .
720-731.