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Blending Basics for Tablet Making

Blending in solid dose manufacturing has two objectives; 1) To achieve blend uniformity and 2) to distribute the lubricant.  In (objective 1) the blend step(s) are designed to achieve homogeneity of all components prior to the final blend of the lubricant (objective 2).  The challenge is that there is no such thing as a perfect blend.  Blending is like shuffling a deck of playing cards; there is just no such thing as a perfect shuffle.  As with shuffling playing cards, blending powders is even more of a challenge due to particle size, moisture content, structure, bulk density and flow characteristics. The bottom line is that blending techniques for tablet making must produce predictable and repeatable results to achieve content uniformity and proper function. The first step in achieving predictable results in a blend is to introduce the proper particle profile within a range; between 40 – 180 mesh for most oral solid dosages.  We do not want any particles larger than 20 mesh and try hard to limit the percentage of fines to less than 20% smaller than 200 mesh.  The next step is to complete pre-blending steps in a carefully planned order of addition.  In other words we need to blend powders with a strategy.  Many formulators blend actives and then excipients, others add based on percentages.  Over the years I have found that the best success is to know your objective.  Simply realize the goal to deliver an active ingredient that holds together, produces predictable results, disintegrates correctly and dissolves when you want it to, only after having sustained the correct shelf life…so what could be the problem?  The best thing is an example of an existing formula; say I have a dry granular formula and a number of overly fine waxy actives, along with a flow agent, bulk agent, and a binder.  My first question is how does it flow, then how does it compress and the how does it eject, then how does it disintegrate, dissolve and stability and shelf life.  I would use the waxy fine particles to coat the larger dry particles to aid compressibility.  Then I would add the binder and bulk agents and test between steps for proper parameters of the deleveloping tablet.  Too many formulas are old recipes without rhyme or reason. Many formulas are excellent but are not blended correctly; the key to a successful formula is the order of addition.  Since each formula is different there are many factors to be considered for each and every formula.  When all ingredients are dumped into the blender, optimization is rarely achieved and many times flow, compression and ejection are put into jeopardy.  The key is proper addition including the lubricant.  Add the lubricant last, by itself; never blend it with anything else, and only blend for a short duration.  Under blending a lubricant is better than over blending it.

 

I hope this helps….any questions or comments please let us know.

 

 

 

Posted by Mike on June 29th, 2009 :: Filed under Blending, Tableting
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Confused about Raw Material Identification Requirements?

I understand there is still a great deal of confusion surrounding the Raw Material Identification requirements in the Dietary Supplement GMP’s. I hear from clients daily that they still don’t know what to do, how to do it, and when to do it. Let’s see if we can help clear up some of the questions folks are having out there!

First off, let’s review the regulations so we know why ID testing is required. According to 21 CFR Part 111, Subpart E, 111.75, “before you use a component, you must conduct at least one appropriate test or examination to verify the identity of any component that is a dietary ingredient” What that means is that for every unique lot of incoming dietary supplement ingredients, you will need to conduct at least one test or examination that will confirm the identity of that material before use approve it for use and use it in manufacturing.

Let’s be clear about the unique lot of incoming components before we move on. Let’s say you receive a shipment of Vitamin C. You ordered 500 kilograms of Vitamin C and the shipment arrives at your dock. When you do your receiving inspection, you have 2 50 kilo boxes of lot#A360, 4 50 kilo boxes of lot#B720, and 4 50 kilo boxes of lot#A470. To comply with the regulations, you would need to conduct your identity test of a sample from lots A360, B720, and A470, so you would need to do three identity tests on this incoming shipment because it contains three different lots of material, even though it’s the same material, received at the same time. Its always a good idea to request that your order be filled with one lot of material whenever possible.

Now that you’ve ID tested those three lots, the next time you get a shipment of Vitamin C, it has two lots; A470 and C220. Provided you have it written in your inspection SOP correctly, you would not need to ID test lot A470 again since you’ve already tested it, but you would need to test C220. Make sense?

The next thing to look at is how to do the ID testing. Since no one test or examination will give you all the identity information you need, you really have to know your materials well to specify what test or examination you will do. I once talked with a client who was struggling with how to test one of his incoming materials. He used broccoli in one of his powders. Yup, raw broccoli! He bought fresh broccoli, dehydrated it, then ground it into a powder and used that in his product. We made the examination simple - if you have raw broccoli, a visual and organoleptic test will definitely identify the material as broccoli since nothing else will look and taste like raw broccoli. If he were to buy the broccoli all dried and powdered, then his test would be different. Then he would need a more complex method like FTIR, HPLC, or some other way to detect the chemical markers that provide broccoli’s unique fingerprint. You must spend the time to get to know your materials well so that you can pick the test or examination that will provide you with certainty that the material is in fact what it needs to be. That may be an HPTLC test or it could be a simple microscopic analysis. The thing is, you get to decide what the test is, as long as you can show it is scientifically valid and will provide you with verification that the material is what it says it is. The regulations state that you can use, “gross organoleptic analysis, Macroscopic analysis, microscopic analysis, chemical analysis, or other scientifically valid methods” so as you can see, you have the ability to be creative with your identity testing. Just be sure whatever method you decide to use provides you with verification that the material is what it needs to be.

I’ll give you another example, back in my manufacturing days, the company I worked for used Zinc Oxide as an active ingredient for an OTC drug product. All OTC ingredients need to be identity tested also. The USP listed several different ways to identify this material. One of them was that when heated strongly, zinc oxide would turn from its original white powder form to a yellow powder, then return to white when cooled. I could have sent the material out for IR testing or another form of chemical analysis, but instead, we specified that heat test as the ID test and it worked. It was scientifically valid, fast, and provided verification that the material was in fact what it needed to be. So you see, you can use a test that may seem too simple, but gives you the information you need. But you MUST spend the time getting to know your materials well first!

I hope this helps answer some of the questions out there.

Carol Brennon, ASQ CQA

Posted by Mike on June 25th, 2009 :: Filed under cGMP's
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