Given that the D90 is 30microns, how much particle size should be increased to delay the dissolution rate of the tablet for 10 minutes?
You are seemingly considering that the tablet is composed from some aggregated powder particles, possibly containing or solely constituted by some Active Pharmaceutical Ingredient (API). Possibly, the tablet first disaggregates to its constitutional powder, which particles then dissolve or somehow leach out their content, what process may (perhaps) be assisted by effect of the stomach acid. This second stage may take significantly longer than the former, being then rate-controlling. The shrinking core model can, in principle, be adopted to describe the kinetics of such process. From this, it follows that the size of the powder particles can be taken as directly proportional to the square root of their dissolving time. The last can, therefore, be expected to increase by approximately four-fold when the characteristic size of the particles doubles, as long as the concentration of the stomach acid can be considered nearly constant when it also participates in the API dissolving process. Also the temperature should be kept constant for both cases. At least two different mean sizes would have to be taken as (experimental) data points, to allow generic predictions for other granulometries, if such predictions are to be solely based on combined granulometric vs. dissolving time data.
The following linked document may possibly be found of some help:
http://umich.edu/~elements/5e/14chap/expanded_ch14_A.pdf
I think it is easier to change levels of disintegrants on your formulation. A Tablet normally is composed by fillers, aglutinants, disintegrants and lubricants. Reduce the disintegrant level, use a non-soluble filler such as dicalcium fosfate and you can change the dissolution as you like, testing levels of each component by Statistical Design of Experiments.
Please consider the size of tablet and method of tablet manufacturing.
If your tablet size is less than 9mm then increasing the particle size will not be a good idea because it may cause non uniformity of dose.
I think increased hardness and excess use of antiadherants like talc may increase the dissolution.
In my opinion particle size may not be decisive in this case.
I think first, you have to use a water-insoluble binder in a high concentration (approximately 10 -15%). Second, you can decrease the concentration of the disintegrant in your formula to the minimum concentration (approximately (2%). Third, replace the filler(s) in your formula with a water-insoluble filler(s) with average particle size distribution (it's not preferable to sieve at very small mesh size, sub-micro range). Fourth, increase tablet hardness.
As for using anti-adherents such as Talc in a concentration (3%), I think it won't literally improve the dissolution. It mainly decreases interparticulate friction and cohesion, and uses with lubricants in order to prevent adhesion to punches and dies. But it might improve the dissolution at a high concentration (10%) to a lesser extend.
I agree with Ahmed too.
Based on my own experience, increasing your binder (such as povidone) will be able to delay it by 10 min. My experience was an increase from 1 % to 4 % did the job.
Hope this helps.
Is there a reason why you want to investigate particle size for reducing dissolution rate?
Thanks everyone.
Wai Ling, I am just thinking since particle size is often decreased to enhance dissolution rate, if the situation is different way around, which is I want to delay my dissolution rate, will it work the same as the previous concept.
Is there any possible way to work this out, or where can I get those experimental data that had already been carried out to investigate the relationship between particle size distribution and dissolution rate of tablet?
Kindly check these references:-
(1) Sun et al., 2012
Effect of particle size on solubility, dissolution rate, and oral bioavailability: evaluation using coenzyme Q10 as naked nanocrystals
(2) Chu et al., 2012
Effect of particle size on the dissolution behaviors of poorly water-soluble drugs
(3) Tromelin et al., 2008
Relationship Between Particle Size and Dissolution Rate of Bulk Powders and Sieving Characterized Fractions of two Qualities of Orthoboric Acid
(4) Buckton and Beezer, 1992
The relationship between particle size and solubility
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3500035/
https://link.springer.com/article/10.1007/s12272-012-0709-3
http://www.tandfonline.com/doi/abs/10.3109/03639049609065928?journalCode=iddi20
http://www.sciencedirect.com/science/article/pii/0378517392901844
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