What Are the Pros and Cons of the Buccal Route? A Pharmacological Review

Over 90% of some medications are cleared during a single pass through the liver, making alternative delivery methods critical. The buccal route, where drugs are absorbed through the cheek's oral mucosa, is one such method. This article details what are the pros and cons of the buccal route to provide a comprehensive pharmacological overview of its benefits and limitations.

Quick Summary

Buccal drug delivery involves placing medication between the gums and cheek to enter the bloodstream directly, bypassing the digestive system and liver. Key benefits include avoiding first-pass metabolism and providing a rapid onset of action, ideal for patients with swallowing difficulties. However, its disadvantages include a limited absorption area, the potential for mucosal irritation, and restrictions on eating and drinking.

Key Points

• First-Pass Avoidance: The buccal route allows drugs to enter systemic circulation directly, bypassing hepatic metabolism and increasing bioavailability.

• Rapid Onset: With a rich blood supply in the oral mucosa, buccal administration can produce a faster therapeutic effect than traditional oral methods.

• Limited Dosage: The small surface area of the buccal mucosa restricts drug administration to low, potent doses.

• Patient-Friendly: This route is suitable for patients with swallowing difficulties and allows for easy removal of the medication if needed.

• Inconvenient Factors: Eating, drinking, or smoking can negatively impact drug absorption and effectiveness during buccal administration.

• Formulation is Key: Advanced formulations using mucoadhesive polymers and penetration enhancers help overcome challenges like washout and low permeability.

Understanding the Buccal Route of Administration

Buccal administration is a method of drug delivery where medication is placed in the buccal pouch, the space between the gums and the inner lining of the cheek, allowing it to be absorbed directly into the systemic circulation through the oral mucosa. This process bypasses the gastrointestinal tract and the liver's first-pass metabolism, which significantly increases the bioavailability of certain drugs. Historically, this route has been used for medications that require a rapid effect or those that are poorly absorbed or destroyed in the stomach.

The Advantages of the Buccal Route

1. Avoids First-Pass Metabolism: The most significant advantage of the buccal route is that drugs are absorbed directly into the bloodstream via the jugular vein, bypassing the liver entirely. For drugs with high hepatic clearance, this can dramatically increase their bioavailability and therapeutic effect, allowing for a lower, more effective dose.
2. Rapid Onset of Action: The oral mucosa is richly supplied with blood vessels, enabling drugs to be absorbed quickly. While typically slower than the sublingual route, it still offers a faster onset than oral ingestion, which is critical in emergency situations, such as a hypoglycemic event or managing seizures.
3. Suitable for Patients with Dysphagia: This route is an excellent alternative for patients who have difficulty swallowing tablets or capsules, including children, the elderly, or those who are unconscious. Buccal preparations, often available as films or gels, can be easier to administer.
4. Patient Compliance and Convenience: The buccal route allows for self-administration and is a non-invasive method. In the event of an adverse reaction, the medication can be easily and quickly removed from the mouth.
5. Potential for Sustained Release: Mucoadhesive delivery systems, such as patches or tablets, can adhere to the buccal mucosa for an extended period. This allows for a sustained release of the drug over time, improving patient compliance by reducing dosing frequency.

The Disadvantages and Limitations of the Buccal Route

1. Limited Absorption Area: The buccal mucosa has a smaller surface area (approximately 50 cm²) for absorption compared to the gastrointestinal tract. This restricts the amount of drug that can be administered, making it unsuitable for large doses.
2. Variability and Inconvenience: Factors like eating, drinking, or smoking can significantly affect drug absorption by altering saliva flow, pH, and the integrity of the mucosa. Maintaining the dosage form in the correct position without chewing or swallowing can be inconvenient for some patients.
3. Mucosal Irritation: Some medications or excipients can cause irritation to the oral mucosa, leading to discomfort or potential damage, especially with prolonged use or potent drugs.
4. Taste and Palatability: Drugs with an unpleasant or bitter taste are poorly suited for buccal delivery, as it can lead to voluntary expulsion and decreased patient acceptance.
5. Washout Effect of Saliva: The constant secretion of saliva can lead to the accidental swallowing of dissolved medication, which may be degraded in the stomach or pass through first-pass metabolism anyway, reducing the intended effect.

Dosage Forms and Overcoming Challenges

Drug developers utilize various formulation strategies to maximize the benefits and minimize the drawbacks of the buccal route. These include:

• Mucoadhesive Polymers: These are incorporated into dosage forms like films and patches to prolong the residence time of the drug on the mucosa, increasing contact time for better absorption.
• Penetration Enhancers: Chemical enhancers, such as surfactants or fatty acids, can be added to formulations to reversibly increase the permeability of the buccal mucosa.
• pH Modifiers: The pH of the saliva can influence a drug's ionization and absorption. Formulations with pH modifiers can optimize the microenvironment to enhance absorption.

Comparison of Buccal and Oral Routes

Feature	Buccal Route	Oral Route (Swallowed)
First-Pass Metabolism	Avoids hepatic metabolism.	Susceptible to extensive hepatic metabolism.
Onset of Action	Relatively rapid.	Variable and generally slower.
Patient Compliance	High for certain formulations (e.g., films). May be inconvenient if taste is an issue or if eating/drinking are restricted.	High acceptance, convenient.
Dose Limitations	Generally limited to small, potent doses.	Can accommodate a wide range of doses.
Suitability for Patients with Dysphagia	Excellent alternative for patients with swallowing difficulties.	Requires the ability to swallow effectively.
Effect of Food/Drink	Highly sensitive to eating, drinking, and smoking.	Can be influenced by food, but generally less sensitive to immediate intake.
Risk of Irritation	Possible irritation to the oral mucosa.	Possible irritation to the GI tract lining.

Conclusion

The buccal route of administration offers a valuable alternative for drug delivery, particularly for medications that benefit from bypassing the liver's first-pass metabolism, requiring rapid absorption, or needing a sustained-release profile. It is a compelling option for patients who cannot swallow conventional tablets. However, its effectiveness is balanced by significant limitations, including a small absorption area, potential irritation, and the inconvenience of avoiding eating and drinking. Ongoing pharmaceutical innovations, such as advanced mucoadhesive polymers and penetration enhancers, continue to address these challenges and expand the therapeutic applications of buccal drug delivery. As the field evolves, the buccal route is likely to become an increasingly important tool in personalized and patient-friendly medicine.

For more detailed information on advanced delivery systems, you can consult authoritative sources like Buccal Drug Delivery Systems | Nature Research Intelligence.

Frequently Asked Questions

How does the buccal route differ from the sublingual route?

The buccal route involves placing medication between the cheek and gum, while the sublingual route is under the tongue. The sublingual mucosa is thinner and more permeable, offering a faster onset of action, whereas the buccal mucosa is thicker, allowing for more sustained-release formulations.

What kind of medications are typically given buccally?

Buccal delivery is often used for drugs that are destroyed by stomach acid, have a high first-pass metabolism, or require a rapid onset of action. Examples include some opioids like fentanyl and certain hormonal medications.

Can I eat or drink while taking buccal medication?

No, it is recommended to avoid eating, drinking, and smoking until the buccal medication has fully dissolved. These activities can disrupt the medication's contact with the mucosa, reducing its effectiveness and potentially causing it to be swallowed.

Is the buccal route safe for patients with oral infections or injuries?

Buccal administration is contraindicated in patients with severe oral infections or injuries, as it can cause irritation and potentially worsen the condition. Any open sores in the mouth can also become irritated by the medication.

What are mucoadhesive polymers and why are they used in buccal formulations?

Mucoadhesive polymers are substances that help a dosage form, such as a tablet or film, stick to the oral mucosa. They are used to increase the contact time between the drug and the absorption site, which helps sustain the drug's release and improves absorption.

How can the taste of buccal medication be managed?

For medications with an unpleasant taste, pharmaceutical companies use flavoring agents to improve palatability. However, this is not always possible, and a bad taste can still be a reason for patient non-compliance.

Is buccal administration suitable for long-term drug delivery?

While mucoadhesive formulations can provide sustained release, the buccal route is not typically preferred for very prolonged or frequent administration due to the potential for discomfort and inconvenience. Topical side effects, such as irritation, may also occur with chronic use.