Enteric coating is a critical technology in pharmaceutical manufacturing, especially for protecting tablets from stomach acid and enabling targeted intestinal drug release. For procurement specialists and pharmaceutical manufacturers evaluating tablet coating systems, understanding how enteric coating works is essential.
This guide explains the enteric coating mechanism, commonly used polymers, and the complete tablet coating process, while offering practical insights into equipment selection, including tablet coating pans, fluid bed coaters, and modern pharmaceutical coating machines.
Introduction
Ever wondered why some tablets don’t dissolve in the stomach but instead release their active ingredients in the intestines? That controlled behavior is achieved through enteric coating.
In pharmaceutical production, enteric coating not only protects acid-sensitive drugs but also improves patient compliance and product stability. For procurement teams sourcing coating equipment for tablets, a clear understanding of this process ensures the right investment in both materials and machinery.
What Is Enteric Coating?
The Basic Mechanism
Enteric coating is a pH-sensitive protective film applied to oral solid dosage forms such as tablets and capsules. The coating withstands the acidic environment of the stomach (pH 1–3) and dissolves only in the higher pH of the small intestine (pH 5.5–7.5).
Remains intact in gastric conditions, preventing premature drug release
Dissolves in the intestine to release the active ingredient
Protects acid-sensitive drugs and minimizes gastric irritation
Achieving this behavior requires precise control during the coating process, highlighting the importance of reliable tablet coating machines or fluid bed coaters.
Selecting the right polymer depends on drug formulation, target release profile, and equipment capabilities.
The Enteric Coating Process Explained
Step-by-Step Overview
1. Preparation of Core Tablets Tablets must have sufficient hardness, low friability, and controlled moisture content to prevent defects during coating.
2. Formulation of the Coating Solution Enteric polymers are dissolved or dispersed in water or organic solvents, often combined with plasticizers and pigments for film flexibility and appearance.
3. Application Using Coating Equipment Tablets are processed in a tablet coating pan, perforated pan, or fluid bed coater.
Spray rate, inlet air temperature, pan speed, and atomization pressure are key parameters
Modern tablet coating systems ensure uniform film thickness and minimal defects
4. Drying and Curing Further drying removes residual solvents and allows the polymer film to cure properly.
5. Quality Control Checks include dissolution testing, coating thickness measurement, and visual inspection to confirm compliance with specifications.
Uniform film coating and stable dissolution profiles
Reduced defects like peeling, cracking, or color variation
Improved throughput and repeatability
Depending on production needs, manufacturers may select tablet coating pans, film coating machines, or fluid bed coaters for optimal performance.
Case Studies: Real-World Applications of Enteric Coating
Case Study 1: Protecting Acid-Sensitive Drugs A manufacturer needed to protect an API that degraded in gastric acid. By switching to a methacrylic acid copolymer system and upgrading to a precision fluid bed coater, the company achieved consistent enteric release. Strategic equipment procurement proved critical.
Case Study 2: Reducing Stomach Irritation Another manufacturer faced customer complaints of gastric irritation from an oral analgesic. Implementing CAP-based enteric coating and optimizing tablet coating pan parameters reduced irritation while maintaining efficiency.
Key Points to Remember
Enteric coating protects tablets from stomach acid and enables intestinal release
Polymer selection depends on drug properties, target pH, and coating method
Stable, GMP-compliant coating equipment is critical
Equipment choice affects product quality, throughput, and defect rates
Procurement teams should evaluate cost, performance, and long-term service
Useful Resources and Further Reading
FDA Guidance on Coating of Oral Solid Dosage Forms
Pharmaceutical Coating Technology – ScienceDirect
Eudragit® Polymers Overview – Evonik
Tablet Coating Machines Explained – GEA Pharma Systems
Conclusion
Understanding enteric coating is essential for pharmaceutical manufacturers and procurement professionals. Beyond formulation, success relies on selecting GMP-compliant tablet coating machines, pill coating machines, or fluid bed coaters that deliver consistent, defect-free results.
JIANPAI offers high-quality tablet coating solutions for film, enteric, and sugar coating applications. Partnering with a reliable equipment supplier helps improve coating quality, reduce production risks, and ensure long-term manufacturing success.
Frequently Asked Questions (FAQ)
Q1: What is the main purpose of enteric coating? A1: To protect tablets from stomach acid and enable controlled intestinal release.
Q2: Which polymers are commonly used for enteric coatings? A2: CAP, methacrylic acid copolymers (Eudragit®), and HPMCP.
Q3: Can enteric coating be applied using different coating equipment? A3: Yes, including tablet coating pans, film coating machines, and fluid bed coaters, depending on formulation and scale.
Q4: What defects can occur during the coating process? A4: Peeling, cracking, or uneven film thickness, often due to improper equipment settings or formulation.
Q5: How does coating equipment choice affect production time? A5: High-performance tablet coating systems reduce coating time while maintaining quality.
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