As discussed in our previous blog, drug products can be optimized by instilling mucoadhesive properties.

Mucoadhesion is the adhesion of synthetic or biological macromolecules to biological tissue, most frequently a mucus or mucous membrane. This adhesion is held together for extended periods by interfacial forces. Mucoadhesion can be incorporated into a variety of drug delivery systems; these could be for buccal, sublingual, vaginal, rectal, nasal, ocular, or gastrointestinal administration, etc.

In this blog, we discuss key initial formulation considerations when designing mucoadhesive dosage forms, such as those involving the drug, inactive ingredients, and intended site of action.

What to consider when formulating for mucoadhesion

When designing a mucoadhesive drug formulation, there are factors that must be considered to ensure the target product profile (TPP) is reached.

Active pharmaceutical ingredient/s (API/s)
The formulation of mucoadhesive drug products depends on the physicochemical properties (such as stability, solubility, and permeability) of the API (e.g., size, stability, solubility, permeability), and dose strength requirements.

Excipients
When designing a mucoadhesive formulation, it is critical to select an excipient that can impart mucoadhesive properties and ensure prolonged retention of the formulation at the site of action. For an excipient to be mucoadhesive, it must be a synthetic or natural hydrophilic polymer containing functional groups that can interact with mucin glycoproteins. This interaction occurs via non-covalent bonds, such as hydrogen bonding, van der Waals forces, and ionic interactions

There are several polymers that are used across the pharmaceutical and healthcare industries to create and enhance mucoadhesion in product formulations, such as:

Carbomers (e.g., Carbopol^®polymers)
Xanthan gum
Carrageenan
Copolymer of methyl vinyl ether and maleic anhydride (PVM/MA)
Hydroxypropyl cellulose (HPC)
Sodium carboxymethylcellulose (Na-CMC).

Moreover, the choice of additional inactive ingredients is also vital, as they may alter the API release rate, stability, and permeation, among other properties.

Intended site of action
The objective in creating a mucoadhesive formulation is to enable the effective delivery of an API to the target tissue for the desired therapeutic effect. As such, it is crucial to consider the unique properties of different mucosal tissues. This entails understanding tissue penetration, as not all surfaces have the same properties. For instance, drug uptake through the vaginal mucosa differs from that of the nasal or oral mucosae. Moreover, there can be differences in permeability between different regions of the same cavity (e.g., for oral cavity - sublingual, buccal and palatal).

In addition, the formulation must be optimized for either localized or systemic drug delivery, as mucosal formulations can enable either approach depending on the dosage form.

Dosage Form
It is possible to develop a wide variety of mucoadhesive dosage forms, including liquids, semi-solids, and solids. The chosen formulation base will depend on the TPP, the route of administration, the indication being treated, and the API, among other attributes. It is also important to bear in mind patient convenience and treatment adherence when selecting a dosage form.

Dosage forms that can be enhanced with mucoadhesive properties include:

Films
Oral solutions and suspensions
Topical gels and emulsions
Nasal sprays
Lozenges and buccal tablets
Toothpastes and mouth washes
Eye drops

LLS Health and mucoadhesive dosage forms

Polymer excipients are essential ingredients in any effective mucoadhesive drug formulation. However, not all mucoadhesive polymers have the same performance. Selecting the right excipient and supplier are key to developing effective formulations.

LLS Health has decades of experience with mucoadhesive dosage froms. Our Carbopol^® polymers and Noveon^® polycarbophil have proven success providing significantly improved mucosal product retention at the target site when compared to products containing alternative polymers.

To learn more about mucoadhesion, its benefits, and mucoadhesive polymer options, download our latest guide and technical brief.

Guide: Initial Formulation Considerations for Mucoadhesive Drug Products