Buccal drug delivery enables drug absorption through the inner cheek (buccal mucosa), bypassing liver metabolism and offering improved bioavailability.
Types of Buccal Dosage Forms
Mucoadhesive Tablets
Components: Mucoadhesive polymers (HPMC, chitosan), permeation enhancers.
Advantages: Prolonged release, enhanced bioavailability.
Challenges: Adhesion in a moist environment, release control.
Patches and Films
Components: Polymeric matrix (PVA, polyethylene oxide) with plasticizers.
Advantages: Comfortable, fast onset, uniform distribution.
Challenges: Ensuring mucoadhesion, drug uniformity.
Semisolids and Powders
Advantages: Simple formulation, fast onset.
Challenges: Distribution uniformity, saliva washout.
Mechanisms of Buccal Absorption
Passive Diffusion:
Drugs move from high to low concentration across the buccal mucosa, common for lipophilic drugs.
Carrier-Mediated Transport:
Drugs are transported across the mucosa by specific proteins.
Endocytosis:
The cell membrane engulfs drug molecules, internalizing them.
Factors Affecting Buccal Absorption
Drug Properties: Lipophilicity, size, ionization, and solubility.
Saliva Flow Rate: Dilutes and washes away drugs.
Buccal Health: Conditions like inflammation can affect absorption.
Formulation Factors: pH, viscosity, and excipients.
Advantages of Buccal Drug Delivery
Bypassing First-Pass Metabolism: Direct systemic absorption.
Enhanced Bioavailability: Ideal for drugs with first-pass metabolism.
Rapid Onset: Suitable for fast-acting drugs.
Improved Compliance: Non-invasive, convenient.
Limitations
Drug Limitations: Only suitable for certain drugs.
Saliva Dilution: Reduces drug concentration at the site.
Potential Irritation: Formulations may irritate the mucosa.
Patient Variability: Buccal pH, saliva production affect absorption.