Coating problem

(Sajjad Ahmad) #21

coating dispersion percentage?

(Sajjad Ahmad) #22

tablet bed temp?

(Elena Ponkratenkova) #23

45-46 C

(Elena Ponkratenkova) #24

yes, we tryed various spray and atomising pressure

(Elena Ponkratenkova) #25

it’s not peeling and tablets are not wet during coating

(Elena Ponkratenkova) #26

coating suspension percentage - 9,7

(Rahul Kumar ) #27

Try to use PG instead of PEG( Macrogol)
This is Plasticizer Problem

(Sajjad Ahmad) #28

coat at bed temp of 38_41

(Elena Ponkratenkova) #29

Ok, I’ll try.Thanks.

(Elena Ponkratenkova) #30

It’s impossible. I can’t use it instead of macrogol, I must use only macrogol.

(Sajjad Ahmad) #31

at 45’46 bed the micro enviornment of pan is totly changed

(Elena Ponkratenkova) #32

but sending site has the same bed temperature but doesn’t have these defects

(Sajjad Ahmad) #33

Coating machine efficiency vary that effects.

(Savinay) #34

Dear Elena,

I have checked the picture of defective tablets. The following are my observations:

  1. The white spots on edge of tablets: The tablet edges sometime develop collars. This may be due to compression on tablets at higher hardness, due to the gap between the die wall and the upper punch or due to worn out tools. These edges will be soft. During coating, there will be load on tablets and attrition due to rotation of the pan. Therefore, there are chances that these soft edges break and will result is white patches.
    Punch design to be modified to avoid this type of defects.
  2. The tablet with logo 10 & 20: The depth of the logo “0” to more. Due to this, there will be formation of weak areas. Due to load on the tablets during coating, there are changes that these soft areas get eroded. If the formulation contains super disintegrates, then the disintegrate may absorb the droplets and swell resulting in erosion of surface and white patches.
    Punch design to be modified to avoid this type of defects.
  3. From the picture it also appears that few of the tablet defects are resulting due to strong attrition within the coating pan. There may be some sharp edges that may be resulting these defects. Get the coating pan inspected. This may also be generated when the tablets hit the baffles hardly. Check on the coating pan speed as well.
  4. Other precautions that may be considered:
  • Pre-warming of tablets until the bed temperature attains 45˚C. Start spraying as soon as the bet temperature attains. Pre-warming for longer time, in some formulations, result in loss of moisture from tablets and then on spraying the coating solution, surface erosion can occur.
  • Since the coating solution is aqueous, the bed temperature can be taken upto 48 ˚C also during coating process.
  • Initially start the spraying with low spray rate, and then gradually increase. If require, you can again reduce the spray rate towards the end of coating.
  1. What is the weight build that you that you are providing to tablets?



(Elena Ponkratenkova) #35

Thank you very much!
Weight of cores 85 mg and coating tablets - 87.5 mg

(Sajjad Ahmad) #36

According to my practical observatons 48 tab bed temp is very high and not suitable bcz of follwing observations of mine
Above 44 degree the humidity level inside closed pan increases due to excessive evaporation of water and it disturb tab bed movements.bed come close to guns and tabs may become wet.
2ndly above 45 recomended moisture level in grains is also dried n tab avg wt is also decreased.
(Above observations vary product to product)
According to my observations and experience aqueous coating bed temp is very suitable in betwen 38_43.

(Savinay) #37

Dear Elana,

Please lets us know what steps you implemented to over come the defects.

Thanks & Regards,


(Elena Ponkratenkova) #38

Dear colleagues,

first of all I’m going to change the approach to the preparation of coating suspension, because I have already done: pre-warming of tablets, coating bed temperature 38-42C, different spray rates and drum speed and their combinations etc. with out results.
I can do it only in mid - March. After that I’ll most certainly inform you.
Tanks a lot for your advices.

(vijay kumar) #39

can u send me the coating procedure… I will try to resolve ur problem