Empty Enteric Coated Capsules vs. Film-Coated Tablets

When it comes to pharmaceutical dosage forms, the choice between empty enteric coated capsules and film-coated tablets can significantly impact drug delivery, efficacy, and patient compliance. Both dosage forms offer unique advantages, making them suitable for different therapeutic needs. In this blog post, Wecaps will share with you the comparison of empty enteric coated capsules and film-coated tablets, examining their formulations, mechanisms of action, and applications.

1. Formulation and Structure

Empty Enteric Coated Capsules

Empty enteric coated capsules consist of a gelatine or hydroxypropyl methylcellulose (HPMC) shell that encapsulates the drug. The enteric coating, typically made from polymers like methacrylic acid copolymers (e.g., Eudragit® L or S), is designed to resist dissolution in the acidic environment of the stomach but dissolve in the more alkaline environment of the small intestine. This coating prevents the drug from being released until it reaches the desired location in the gastrointestinal tract.

The formulation of enteric coated capsules involves several critical steps:

- Capsule Shell Preparation: The shell is produced from either gelatine or HPMC, offering different properties such as solubility and flexibility. Gelatine is derived from animal collagen and is widely used due to its cost-effectiveness and established history. HPMC, a plant-derived polymer, is used for vegetarian formulations and provides greater control over capsule disintegration.

- Enteric Coating Application: The enteric coating is applied through spray coating techniques. This coating is formulated to be stable in the acidic gastric environment and to dissolve only at a specific pH, usually above 5.5.

Film-Coated Tablets

Film-coated tablets are solid oral dosage forms where a thin film of polymer is applied to a compressed tablet core. The film coating, composed of various polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), or ethylcellulose, serves multiple purposes: protecting the tablet core, masking taste, and modifying drug release.

The formulation process of film-coated tablets includes:

- Tablet Core Preparation: The core tablet is manufactured through direct compression or granulation methods, containing the active pharmaceutical ingredient (API) along with excipients such as binders, fillers, and lubricants.

- Film Coating Application: The coating solution or dispersion is applied to the tablet core using techniques such as pan coating or fluidized bed coating. The film forms a protective layer that can be designed to be either immediate-release or extended-release, depending on the desired drug release profile.

2. Mechanisms of Drug Release

Empty Enteric Coated Capsules

The enteric coating on these capsules is specifically designed to resist dissolution in the stomach’s acidic environment. This mechanism ensures that the drug is not released until the capsule reaches the more neutral pH of the small intestine. The key advantages include:

- Protection of Acid-Sensitive Drugs: Drugs that are unstable or poorly absorbed in the stomach's acidic environment benefit from enteric coating.

- Localized Drug Delivery: The enteric coating allows for targeted delivery of drugs to the small intestine or specific regions of the gastrointestinal tract.

Film-Coated Tablets

Film-coated tablets can be designed for various drug release profiles, including immediate, extended, or delayed release. The film coating acts as a barrier that can influence the drug's release in several ways:

- Immediate Release: For rapid drug absorption, the film coating is often designed to dissolve quickly in the stomach.

- Extended Release: For prolonged drug action, the film can be formulated to gradually release the drug over time.

- Delayed Release: Similar to enteric coating, film coatings can be designed to release the drug in the intestines.

3. Applications and Suitability

Empty Enteric Coated Capsules

Empty enteric coated capsules are particularly suitable for:

- Acid-Labile Drugs: Drugs that degrade in acidic conditions benefit from enteric coatings.

- Targeted Drug Delivery: Conditions requiring localized drug delivery in the small intestine, such as certain gastrointestinal disorders, are well-served by enteric coated capsules.

Film-Coated Tablets

Film-coated tablets are versatile and suitable for:

- Immediate Release Needs: Quick dissolution and absorption are achievable with appropriate film formulations.

- Extended or Controlled Release: Films can be engineered to provide extended drug release, which is beneficial for chronic conditions requiring stable drug levels.

Empty enteric coated capsules and film-coated tablets are both advanced pharmaceutical dosage forms with distinct benefits and applications. Enteric coated capsules offer targeted release and protection for acid-sensitive drugs, while film-coated tablets provide flexibility in release profiles and additional benefits such as taste masking. The choice between these dosage forms depends on the specific drug properties, therapeutic goals.