No it is not necessary

Answer would be case by case.

Any drugs approved on the condition of constant monitoring of its effect by company. No company can do research in every part / community of the world. Genetics are different based on several criteria like tropical, food habits, environment etc. Hence study is required to be conducted locally at your setup / hospital for optimal results. For example Phenytoin study revealed in my colleague study, that recommended doses are not fulfilling therapeutic requirements.

My answer is yes for long term prescription drugs.

Hi.

Actually it depends on how much the existing data provide complete and clear evidence and also are some factors about such drug which can compete the existing data? if the power of existing evidences are really convincing, there is no reason to conduct another trial. with respect, I am not agree with Ramesh Babu answer! designing smaller local trials probably can not provide powerful evidence compare to large trials even they results show difference, it could be in doubt how much the data are powerful. Of course the history of some drugs like phenytoin is different because there are many inter and intra patients differences in their pharmacodynamics and pharmacokinetics, but in case of many other drugs, these differences are very low. by the way, there are so many studies in the area of that drugs and their history almost has gone to end !

First I would question as Kourosh is saying what evidence of comparative safety and efficacy exists. Head to head trials might be lacking fairly often and evidence would be established using indirect comparisons and expert opinions quite often. So the robustness of evidence is quite often lacking (safety even more so than efficacy). What can then a study in a hospital add? Most often not all that much, however it might be some special cases such as specific populations that have been less studied (e.g. pediatric populations, special off-label indications) where even a single centre study might be useful.

Finally for some types of drugs with common side-effects and clear outcomes such as cancer meds, it might be worth and interesting to collect data for an in-house registry, that way it would be possible to compare drugs retrospectively to get some hospital specific data to inform decisions on internal guidelines etc. They should always be weighted against the extra burden on phycicians etc. that should be minimized and also it would work less well for drugs with long term outcomes or very rare serious side effects.. It would not really be needed but it would provide data directly related to your specific setting, and such a data collection could also be used to see the effect of organisational changes and other local changes over time which is a different matter but not unimportant.. :)

I'd like to add a short comment to our previous discussion: our sources are limited in all aspects of science, so it would be resonable to evaluate precisely "how much will be useful our new trial and to who extend can help to develope valueable findings? If the answer is that: spending time, money and resources is justifiable for some findings, so we can start the study.

Yes, continued assessment of the drugs after they have past clinical trials and are being used in the market are needed and very relevant. Especially on the safety in addition to further analysis of its efficacy in various populations which can not be all assessed during clinical trials.

All are very good opinions..just like to add one of my one...CLASS EFFECT.......

Yes, it is nesseccary, since the latest findings revealed unequal efficy of generics and brand drugs.

I agree with Marianne Levon Shahsuvaryan. As long as there are (any) changes in the  formula and this includes the pharmaceutical formulas too as these may be different leading to different pharmacokinetical behaviour and manifestations for the same drugs therefore different therapeutic and safety patterns. As an example think on differences in dose fractions for different manufacturers for a start,  absorption and gut disintegration for oral medication en so on.

By same category I assume you mean mechanism of action? If this is the case then yes, not all beta blockers are the same.

If you mean the same drugs with the same formulation then that depends on the groupds of patients being treated, hospital patients are older sicker and have worse renal and liver function.

The answer is don't assume anything, get the data.

I agree with the suggestion mentioned in above. It may differ case by case, inter and intra patients’ differences for the pharmacodynamics and pharmacokinetics of different drugs, variations in environment, region of the World, diet and a number of other factors.

I agree with Dr. David Ferry, Dr. Kristian, Dr. Marianne, Dr. May and Dr. Hatem, Dr. Moses. Whereas, other aspects explained by Dr. Ramesh, and Dr. Kourosh are also important.

We have to make consideration of the mode of action of drugs and importance of the data as pointed out by Dr. David Ferry.

It is not necessary if there is a clear benefit with strong and unbiased clinical evidence favoring the use of one drug over another, especially if your patient is similar to patients in studies that have shown such a difference in therapeutic effects. However, we often encounter situation where we do not have such a prior head-to-head comparision of the therapeutic effects of drugs in the same group. Nevertheless, it is well known that decision-making should should be always based on integrating the best evidence from literature and on the clinical experience of individual clinician (if any), with respect and satisfaction of the individual patient's preferences, needs and values.