Nirali ★ India, 20101110 10:13 Posting: # 6135 Views: 20,546 

Dear friends, I have received a regulatory query to check disso similarity. Query is: To do a statistical comparison of the dissolution profiles of the 10mg and 20mg strength at PH 6.8 according to the  "Model Independent Multivariate Confidence Region Procedure”. Calculate confidence interval of Mahalanobis distance (DM) and a respective similarity limit (RD). (Reference: Dissolution Testing of Immediate Release Solid Oral Dosage Forms, U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER), August 1997) as described in the revised module 3.2.P.2.2). My data is: I have two software: SAS 9.1.3 (but not having SAS/IML) and WinNonlin 5.3. SAS 9.1.3 also not supporting to Hotelling's T² method. Is there any other SAS program to calulate above model with SAS/STAT? Pl. guide me to resolve the query. Thank You. Regards, Nirali Edit: Category changed. [Helmut] 
Nirali ★ India, 20110421 10:27 @ Nirali Posting: # 6930 Views: 15,454 

Dear Friends, I am awaiting for response. Pl. guide me if any idea regarding above mentioned post. Thanks & Regards, Nirali — Nirali Mehta (PHARMASTATS) 
Aceto81 ★ Belgium, 20110428 13:14 @ Nirali Posting: # 6966 Views: 15,418 

Hi, As this question comes up from time to time, I found the following reference: http://wenku.baidu.com/view/01246164783e0912a2162a08.html I'll write a function in R, but I'm short in time for the moment. Maybe after the weekend. Good luck Ace PS: for those who want to play with the data in R: m.ref < 
d_labes ★★★ Berlin, Germany, 20110429 13:14 @ Aceto81 Posting: # 6973 Views: 15,692 

Dear Ace, there is a function mahalanobis() in the stats package, i.e in the base installation of R. But unfortunately it gives no confidence interval out of the box. And this is the tricky part I think and for that I wish you a nice weekend . Beside the Tsong paper which is cryptic in this respect and doesn't give ready to program advice have a look at this online resource for another method: B. Reiser "CONFIDENCE INTERVALS FOR THE MAHALANOBIS DISTANCE" Needs some postscript reader. Have also a look at the function ginv() of the MASS package, which implements the MoorePenrose inverse which is necessary in calculating the Mahalanobis distance if the estimated variancecovariance matrix is not invertible. If you are interested, I have some code ruins. — Regards, Detlew 
yicaoting ★ NanKing, China, 20111006 14:03 (edited by yicaoting on 20111006 14:18) @ Nirali Posting: # 7434 Views: 16,381 

Dear Nirali, I am the developer of DDSolver, an Excel addin for analysis of drug dissolution data. Have you tried DDSolver? It can be accessed here. This program was developed during my Ph.D study years. It is able to calculate Ms's distance and it's 90% confidence interval. Hope it can help you. Although users are forbidden to see the code inside the program, it is not important for pharma scientists. If you want to use DDSolver to calculate Ma's distance, I can promise that I have compared the results of DDSolver with that of the famous paper which might be practically recommended by FDA. Moreover, I have compared DDSolver's Ma's distance with that of Mathematica. Mathematica is a famous numerical analysis software. Both comparisons are high satisfactor. Finally, let me use your data to calc Ma's distance and it's 90%CI. The results are as follows: Some explanations: the conclusion of Reject is obtained based on Max Difference of 10% in between mean dissolution profiles through all the sampling time points as a similarity limit. I used 10mgformuation as a Reference formulation. Alternatively, you can specify a certain Ma's distance value as similarity limit which can be obtained from two bathes of your stardard formulations. To do this, you can use DDSolver's MSD Determination for FrationTime Data module. I am very glad if someone can compare DDSolver's results with that of other programs. 
Nirali ★ India, 20120703 05:40 @ yicaoting Posting: # 8879 Views: 14,353 

Dear All, Thank you for response. I have installed DDSolver and it is very helpful to me. Regards, NIRALI — Nirali Mehta (PHARMASTATS) 
d_labes ★★★ Berlin, Germany, 20120706 08:54 @ yicaoting Posting: # 8900 Views: 14,676 

Dear yicaoting, » If you want to use DDSolver to calculate Ma's distance, I can promise that I have compared the results of DDSolver with that of the famous paper which might be practically recommended by FDA. Moreover, I have compared DDSolver's Ma's distance with that of Mathematica, Mathematica is a famous numerical analysis software. » Both comparisons are high satisfactor. if I got it right (I can't see your code) you calculate the 90% CI of the MD simply as: MD + sqrt(Fval/K) with K the scaling factor and Fval the critical F value from the Tsong et. al. paper. Is this really that simple? How does this fit into the lagrange multiplier method mention in that paper? How does this compare to the method of calculating CI's of MD elaborated in Reiser, B. (2001) "Confidence Intervals for the Mahalanobis Distance" Communications in Statistics. Simulation and Computation, 30, 3745 online resource implemented in SAS (needs module IML) described here. BTW: The Tsong et al paper can be found in downloadable form via this link. — Regards, Detlew 
Sid ☆ Singapore, 20190307 18:23 @ yicaoting Posting: # 20008 Views: 4,459 

I am using DD solver, however it is online giving me following statics p (sampling points) K (scaling factor) F_(p,n1+n2p1,0.90) Hotelling's T^2 Mahalanobis Distance (MSD) Lower_90_CR_MSD Upper_90_CR_MSD I am not able to see Max_MSD. can you please guide me how to calculate this from the same data that is shared above. Also, help me understand why am I not getting Max MSD calculations in the MSD for Fractiontime data 