Common Problems in Enteric Coating: Troubleshooting & Machine Solutions

Introduction

If you’re diving into the world of pharmaceutical manufacturing, you know that Enteric Coating is a delicate art. It protects tablets from stomach acid, ensuring the drug releases exactly where it should—in the intestines.

But, as any production manager knows, this process is prone to failure. From “orange peel” surfaces to tablets sticking together (“twinning”), these defects cost time and money.

While formulation plays a role, 80% of coating defects can be solved with the right equipment. Understanding these common problems and tackling them with a high-precision tablet coating machine is the key to a zero-defect batch.

Common Issues in Enteric Coating

Poor Coating Adhesion (Peeling)

One of the most frustrating problems is when the enteric film peels or flakes off the tablet surface.

• The “Formulation” Reason: Hydrophobic tablet surface or insufficient binder.

• The “Machine” Reason (More Likely): Inconsistent spray atomization. If your spray guns are cheap or clogged, they spit large droplets instead of a fine mist. These large droplets don’t stick; they sit on the surface and peel off later.

• The Solution: Use a Jianpai Automatic Coating Machine equipped with imported anti-bearding spray guns. High-precision atomization ensures the coating bonds tightly to the tablet core.

Cracking and Chipping (Internal Stress)

Cracks in the enteric layer compromise the acid-resistance barrier, leading to batch rejection.

• The Cause: Often caused by thermal expansion mismatch. If the tablets are dried too fast or at too high a temperature, the film becomes brittle.

• The Solution: You need precise thermodynamic control. Modern pill coating machines with a PLC-controlled airflow system allow you to ramp up the temperature gently, relieving internal stress in the polymer film.

Inconsistent Coating Thickness (Weight Variation)

For enteric tablets, thickness isn’t just cosmetic; it’s functional. Thin spots allow acid to penetrate, destroying the drug.

• The Cause: Dead spots in the coating drum (pan). If the baffles don’t tumble the tablets effectively, some get coated 10 times, others only twice.

• The Solution: Jianpai’s streamlined baffle design ensures a “dead-zone free” tumbling action. This guarantees that every single tablet receives the exact same amount of spray, maintaining a low CV (Coefficient of Variation).

Twinning (Tablets Sticking Together)

This is a classic nightmare, especially for capsule-shaped tablets.

• The Cause: Over-wetting. The spray rate is higher than the drying capacity.

• The Solution: A high-efficiency tablet film coating machine balances the Spray Rate vs. Exhaust Air. Our High-Efficiency Series uses a perforated drum to maximize airflow through the tablet bed, drying the coating instantly before tablets have a chance to stick.

Environmental and Safety Concerns (Solvents)

Many enteric coatings use organic solvents, which pose explosion risks.

• The Solution: If you use solvents, you cannot use a standard machine. You need an Explosion-Proof Tablet Coating Machine. Jianpai offers fully sealed, negative-pressure designs with solvent recovery systems to ensure operator safety and GMP compliance.

Comparison Table: Defects & Machine Solutions

Case Study: Solving the “Cracking” Crisis

A mid-sized pharmaceutical manufacturer in Southeast Asia was struggling with a 15% rejection rate due to enteric coating cracks. They blamed their polymer supplier for months.
Upon consultation, Jianpai engineers discovered their old machine had uneven airflow, creating “hot spots” that baked the coating brittle.
The Fix: They upgraded to a Jianpai High-Efficiency Automatic Coating Machine. The precise inlet air control reduced thermal stress.
The Result: Defects dropped to under 0.5%, and throughput increased by 30% due to the larger drum capacity.

Conclusion

Enteric coating is a sophisticated process with its fair share of hurdles. While chemists often blame the formula, production managers know the truth: your output is only as good as your machine.

Investing in advanced equipment—like the Jianpai High-Efficiency Series—solves these problems at the hardware level. From anti-bearding guns to precise airflow control, we engineer the defects out of the process.

Ready to eliminate coating defects?
Explore Jianpai’s Coating Solutions or read our guide on How to Choose a Tablet Coating Machine to find your perfect match.

FAQs

Q1: What causes “Orange Peel” roughness in enteric coating?
A: “Orange peel” is usually caused by the coating solution drying before it fully spreads out on the tablet. Increasing the spray rate or reducing the atomizing air pressure on your tablet coating machine can fix this.

Q2: How can I prevent tablets from sticking (Twinning)?
A: Twinning happens when the spray rate is too high for the drying capacity. You need a machine with a perforated pan design to increase airflow, or simply reduce the spray rate.

Q3: Why is coating thickness uniformity important?
A: Unlike cosmetic film coating, enteric coating must be uniform to provide acid resistance. Thin spots will cause the drug to dissolve in the stomach, leading to therapeutic failure.

Q4: Can I use a standard pan for enteric coating?
A: It is difficult. Enteric coating requires precise temperature control. A modern Automatic Film Coating Machine with PLC control is highly recommended over manual pans.

Q5: Are water-based enteric coatings better than solvent-based?
A: Water-based is safer and greener, but harder to dry. You need a machine with high-efficiency drying capability (like Jianpai’s High-Efficiency Series) to handle water-based coatings effectively without extending process time.