Unique Coat L-30 D

            (METHACRYLIC ACID COPOLYMER TYPE C)            
ENTERIC COATING BY AQUEOUS SYSTEM
Milky white dispersion, Aqua base coating which in insoluble in acid (pH 5.5) but soluble in pH above 5.5

“METHACRYL|C ACID CO-POLYMER TYPE-C”

UNIQUE COAT L30D is 30% aqueous dispersion of neutral co-polymer conforms to USP/NF 8. EP specifications of 'METHACRYLIC ACID CO-POLYMER TYPE-C", it is insoluble in acidic medium and resistence to gastric fluids. It dissolves in neutral to weak alkaline medium of the small intestine. This property helps to formulation enteric-coated products,
UNIQUE COAT L30D is soluble alcohol and acetone containing 3% w/w water.

UNIQUE COAT L30D Film is transparent, colourless and brittle. Colored film can be formed by use of suitable pigments. To improve elasticity plasticizer can be added as required. this is an aqueous coating system, which reduced use of solvent. Water soluble plasticizer should be used to obtain elastic films.

Polymer Requirement

The polymer requirement for tablet coating depends upon surface area of a tablet. Table list the % polymer requirement for tablets having different average weight.

Avg weight of tablet (mg) of coating
< 100
Between 100-200
Between 200-400
> 400
5to6
4to5
3.5to4
3to3.5

Atentative formulation for enteric coating by solvent process

for 100 kg batch size
for average weight of 200 mg of tablet

Batch Size x polymer % requirement = 100 kg. x 4 = 4 kg dry polymer
                    100                                                  100
                                                                      =        4         = 13.30 kg (30% dispersion)
                                                                              100

Ingredients

Part 1 Polymer Solution

1. Take UNIQUE COAT L3|JD into a vessel and dilute by adding 3,5 lit DM Water under stirring
2. Dissolve Sodium Hydroxide in 2.0 lit DM Water and add to under stirring to above dispersion.
3. Properly mix DiButyle Pthalate and Tween-80 and add it under stirring to above dispersion.
4. Stirring continue for further 15 minute.

Part 2 Pigment Dispersion

1 . Pour DM Water into vessel under stirring.
2. Add talc, titanium dioxide, color lake and simethicone simultaneously.
3. Pass this solution through a colloidal mill for about 10-15 min OR mixunder high speed stirring about
10-15 min.
4. Filter the solution through 60 mesh (250 microns) tilter. The filtered dispersion must be homogenous
and with lumps. It is normally only slightly viscous but never high viscous.
5. Slowly add part-2 to part-1 stir if for 10-15 minutes, The dispersion is ready for colored enteric coating.

Equipment criteria

The coating can be done by spraying above solution on pellets loaded in fluid bed coater, auto coater pan, acella coater or conventional coating pan, Coating pan with min 4-6 baflles gives better result and preferred.

Parameters

Check the following to ensure proper coating of tablets.

a) Pan RPM :

The RPM of pan should be such that attrition of tablet with coating pan is min. higher RPM will break the film of coating on tablets/pills and lower RPM will result in uneven coating, the ideal pan RPM for different size of coating pan are as follows.
Size of pan RPM
24"
36"
42"
48"
60"
10-15
8-12
6-10
4-8
4-6

b) Air Pressure :

Air pressure of spray gun should be controlled to prevent early drying of polymer before coating. It can also block the spray nozzle. The lower pressure will form droplets which result in uneven and rough surface. For best result air pressure of 2.5, 3.5 kg/cm2 is ideal and is to be maintained throughout the coating process.

c) Temperature :

Maintaining ideal temperature of pan and coating solution prevent loss of coating material. In low temperature, tablets will stick to each other in pan. The suitable temperature range is between 30-45°C throughout the coating process.

Cleaning of equipment

1. UNIQUE COAT L30D is readily soluble in alkaline water.
2. Clean with one of the following solution :
     a. 0.1 N Sodium hydroxide
    b. Calcium Carbonate
    c. Sodium Bi-Carbonate
3. Then rinse with DM water.

Testing of Enteric coated tablets :

Once the process of coating is completed the tablets have to be checked in disintegration test machine. First the sample should be checked in simulated gastric fluid as 0.1N HCI solution for 2 hours or as specified in individual monograph without keeping disc on the top of the tablet. On completion all tablets should remain intect. The film should not break from any portion of tablet. After the tablets should be transferred in simulated intenstinal fluid as pH 6.8 phosphate butter with disc on top of each tablet. Check the disintegration test for 60 min or as specified in individual monograph. All tablet should disintegrate completely. lf tablets stick to the disc. Repeat the test without disc.

Advantages

- No ir and health hazards due to aqueous system.
- Less quantity required, hence reducing volume of solution so shorting production time.
- Stability over a broad temperature range.
- Marginal weight gain in tablets.
- Exhibits excellent color value and shelf shine shade.
- Hydrophobic in nature.
- Contain Carboxylic group which is more stable than Pthalate group of Cellulose Acetate Pthalate or Hydroxy
Propyl Methyl Cellulose Pthalate. This helps in better stability.

Toxicity

UNIQUE COAT LD30D a high molecular weight polymer. It is not absorbed by body tissues and is totally safe for human oral consumption. Test for toxicological tolerance show that if does not have pronounced physiological action and is non toxic.

Storage :

At low temperature below 40c and keep away from frost. Keep the content in tightly closed oondition.


Shelf life :

Two years

Packing :

35kg in carboys.