Tableting, defects, and coating

• Flowability:

powder/granules must flow from hopper to die;

assessed by angle of repose.

Flow problems include arching/bridging (arch-shaped obstruction above outlet) and

rat-holing (material discharges mainly through the center).

Compressibility/compactibility:

ability to form a stable compact; module lists Carr’s Index and Hausner’s Ratio as measures.

Machine parts:

hopper holds blend;

feed shoe transfers blend to die;

die determines tablet size/shape;

upper punch compresses;

lower punch ejects;

cam tracks guide punches.

Press types:

single-punch/eccentric press (module states about 200 tablets/min);

rotary press for large-scale production (module states up to 10,000 tablets/min).

Capping

Top or bottom separates partly/completely from tablet body

Lamination

Tablet separates into two or more layers;

air entrapment.

Cracking

Cracks form; rapid expansion, especially with deep-concave punches.

Picking

Material removed from tablet surface and sticks to punch face; high moisture

Sticking

Granules adhere to die wall or build up on punch faces;

high moisture/inefficient drying.

Chipping

Small pieces break off tablet;

low moisture or insufficient binder.

Double impression

Duplicate engraving due to free rotation of engraved punches.

Mottling

Uneven color distribution;

different-colored materials or poor mixing

efect grouping:

process-related = capping, lamination, cracking;

machine-related = double impression;

excipient-related = picking, sticking, chipping; more than one factor = mottling.

Sugar coating

Successive sucrose-based coats;

thick, rounded, polished tablet; can increase tablet size about 50%;

increases disintegration time; logo/break lines generally not retained.

Film coating protective.

Thin, uniform polymer film; small weight gain (module: about 2–3%);

faster and less costly than sugar coating; little effect on disintegration; durable and

Compression coating

A coating shell is compressed around a previously compressed core.

Sugar coating sequence

1. Sealing / waterproofing

2. Subcoating

3. Smoothing

4. Syruping / color coating

5. Finishing / polishing

. Sealing / waterproofing

Prevents premature erosion/disintegration of core; examples: shellac, PVA, CAP, zein, acrylate polymers.

2. Subcoating

Critical step; gummy solution improves bond and rounds edges; gelatin-acacia plus dusting powder (talc/CaCO3

3. Smoothing

Begins smoothing with syrup

4. Syruping / color coating

Rounds and smooths; adds color using concentrated syrup and colorant.

5. Finishing / polishing

Waxes provide final smoothness and sheen; beeswax/carnauba wax.

Film former = polymer; enteric examples include

shellac, CAP, and methacrylic acid polymers

Non-enteric examples include

HPMC, methylcellulose, ethylcellulose, HPC, PVP, PVA, and Na CMC.

Plasticizer =

flexibility/elasticity (glycerin, propylene glycol, PEG, triacetin, castor oil).

• Surfactant =

improves spreadability (Tweens water-soluble; Spans lipid-soluble).

Solubilizing/permeability modifier =

helps body fluids penetrate the film (PEG).

Glossant =

luster; volatile solvent = evaporation; opacifier/colorant = appearance/protection (e.g., TiO2).

Mottling

Uneven color; poor mixing, uneven spray, or migration during drying.

Sweating

Oily film or droplets; ingredient incompatibility or humidity.

Bridging / logo infilling

Coating obscures engraved logo/markings

Erosion

Coating removed by tablet-to-tablet friction.

Cratering

Coating disruption exposes tablet surface, often at porous crown.

Blistering

Poor adhesion/air entrapment during rapid drying.

Blooming

Dulling/fading of coating appearance.

Capsules

are solid dosage forms in which the drug is enclosed in a shell.

Hard gelatin capsules

• Two-piece shell: body and cap.

• Commonly filled with powders, granules, pellets, or other suitable fills.

• Shell moisture and storage conditions matter; avoid excessive heat/humidity.
  
  

Soft gelatin capsules

• One-piece, sealed shell; shell contains gelatin, water, and plasticizer.

• Commonly used for liquids, oils, suspensions, or suitable semisolids; Accogel/Stern process is noted for solid/dry powder SGC fills.

• Gelatin:water:plasticizer ratio = 1:1:0.4–0.6.

Softgel manufacturing processes:

plate process

forms and seals capsules in molds;

Softgel manufacturing processes:

rotary-die process

uses two gelatin ribbons and a wedge that injects fill while dies cut and hermetically seal;

Softgel manufacturing processes:

Accogel/Stern

uses rotary dies and is identified in the module as the process able to encapsulate solid/dry powders into softgels.