Research into Bioequivalence Dear friends in the quest for valuable knowledge Welcome to another shot of research work on bioequivalence (BE). Bioequivalence work will be going on all the time. In two types of situations you will see it happening. One is when a company wants to introduce a new product into the market, it has to show that the new product is bioequivalent to the innovator/ old/established or reference product. Another situation is when researchers are working to see whether there is bioequivalence between some products or when they prepare a new variety of product and compare it with the marketed product. In both these situations bioequivalence studies are done. The scale and design of the studies naturally varies with the situation. Today I want to put before you two such research issues. Bioequivalence study of Folifer- Z (r) a new formulation of sustained release iron and zinc. International Journal of Pharmaceutics, Volume 178, issue 2, 15 February 1999 Pages 171-181. Abdulazim S. Salhab, Suheil M. Zmeili, Mumir N. Gharaibeh, Hamzeh H. Elayan, Elsayyed Sallam, Suleiman Al Delef. The authors wanted to test for bioequivalence between Folifer-Z(r) tablets, which represent a new sustained release iron and zinc formulation and Fefol-Z(r) capsules. The study was done on 30 healthy male subjects. The design was a two way cross over design and it was a randomized study. After administering the product to the volunteers, blood samples were collected over a 24 hour period and the contents of iron and zinc were determined. From these values pharmacokinetic parameters were calculated. These were subjected to statisitical analysis. Results of this study indicated bioequivalence between Folifer-Z(r) tablets and Fefol-Z(r) capsules. They also indicated the inhibition of absorption of zinc by iron in both cases. I want to tell you some interesting things here. As we see in the above study, the BE studies are done in randomized trials and by following some statistical design such as cross over design or latin square design and so on. This will enable the results to be taken with credibility and will help in drawing conclusions with specified confidence levels. The preferred volunteers are adult healthy males. A wash out period of not less than six half lives is kept between two administrations of products. I want to bring your attention to a few more points. Sometimes a clinical equivalence study is done in the place of a BE study. These BE and clinical equivalence studies are especially important in the case of extended release/ controlled release and sustained release tablets. This is because release from these products is more complex than release from simple products like tablets. Let us look at one such study. 1. Clinical equivalence of two tablet formulations of felodipine. B.P Mc Grath, R.W. Watts, D.B. Elmfelolt, Eur J. Clin. Pharmacology (1995) 49: 169-172. In this work the authors wanted to find out whether new formulation of felodipine extended release (FER) tablets which had a 9 mm diameter is clinically equivalent to the established product of 11 mm diameter FER formulation as judged by their anti-hypertensive effect. They concluded that FER 5 mg tablet formulations ( 9 and 11 mm diameter) were clinically equivalent when judged by their anti-hypertensive effect. So we have seen one BE study and one clinical efficacy study. I will tell about pharmacodynamic studies in my next blog which are also done in the place of BE studies in some situations. I invite your questions and comments. References: 1.Bioequivalence study of Folifer- Z (r) a new formulation of sustained release iron and zinc. Abdulazim S. Salhab, Suheil M. Zmeili, Mumir N. Gharaibeh, Hamzeh H. Elayan, Elsayyed Sallam, Suleiman Al Delef, International Journal of Pharmaceutics, Volume 178, issue 2, 15 February 1999 Pages 171-181. 1. Clinical equivalence of two tablet formulations of felodipine. B.P Mc Grath, R.W. Watts, D.B. Elmfelolt, Eur J. Clin. Pharmacology (1995) 49: 169-172. This blog does not contain any plagiarized material.