CVintra # CVinter # CVtotal [Regulatives / Guidelines]

posted by drmuneesh – 2008-11-28 11:37 (6047 d 09:42 ago) – Posting: # 2830
Views: 7,880

Dear HS,

No, I am not talking about the same drug. I have done two studies with two different drugs. I have done one cross-over pilot with drug A which is a known highly variable drug and now I want to plan a pivotal two-way cross-over study. I have done another parallel Pilot with drug B with very long half and now want to plan a pivotal parallel study. I will elaborate my query as under-
Case-1: I have done a two-way cross-over pilot study with drug A and I have calculated the sample size for the pivotal study using SAS considering intra-subject CV of 0.5363 and observed %T/R ratio of 0.9148. The sample size calculated is 175 for two-way cross-over pivotal study as programmed. As the intra-subject CV is > 30% and the drug is known to be highly variable and therefore, I want to use the replicate (four-way cross-over) study design, in that case can I do the pivotal four-way cross-over study with at least half the number of subjects i.e. 88?

Case-2: I have done another pilot study with parallel design for a very long half-life drug B and I have calculated the sample size for the pivotal study using SAS considering total CV of 0.16 and observed %T/R ratio of 112.08. The sample size calculated is 27 for two-way cross-over study as programmed. In that case can I do the pivotal parallel study with at least double the number of subjects i.e. 54?

Please suggest.

Regards
Dr Muneesh Garg

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