OECD - Testing Guidelines used In Drug Research

        What is OECD ?

The Organizations for Economic Co-Operation and Development (OECD) is the International organization for policy making on various dimensions of economy with prime intention to serve world's larger economies. As per the official website of organization, OECD works for developing evidence based international guidelines and policies for social, economical and environmental challenges. Currently headquartered in Paris, OECD has 37 member countries, with more than 1000 locations for regional development and has invested $309 millions for promoting health and safety by involving various governments, leaders, policy makers and citizen. 

         Testing of  Chemicals 

https://theconversation.com/breakthrough-could-end-
animal-testing-in-carcinogen-research-99578

Among the various guidelines developed by OECD, "Testing of Chemicals - Section 4" is the most relevant for all researchers and aspirant. This is the comprehensive guideline prepared from more than 150 internationally agreed testing methods by various authorities and is used specifically for identifying and characterize potential hazards of chemical substances. This guideline is the basis of all the toxicological / pre-clinical studies on 'medicines and  newly discovered potential drugs' all over the world. Amongst almost 100 tests described in section 4, here, I have mentioned few   with most clinical relevance below: 

• 402: Acute Dermal Toxicity
• 403: Acute Inhalation toxicity
• 405: Acute eye irritation/corrosion 
• 407: Repeated dose 28 days oral Toxicity study in Rodents
• 408: Repeated dose 90 days Oral Toxicity study in Rodents
• 409: Repeated dose 90 days Oral Toxicity study in Non- Rodents
• 417: Toxicokinetics
• 420: Acute toxicity stud- Fixed Dose Procedure
• 421: Reproduction / developmental toxicity screening test
• 423: Acute Oral toxicity - Acute toxic class method
• 424: Neurotoxicity study in Rodents
• 425: Acute oral toxicity - up and down procedure
• 426: Developmental Neurotoxicity study
• 451: Carcinogenicity study
• 453: Combined chronic Toxicity/ Carcinogenicity study

Above mentioned test are few examples that includes revised version of similar test developed earlier too. Amendments and revisions are made based upon the various conference conclusions, current availability of testing laboratory/ facilities and scientific needs. 

For example, Acute Oral toxicity study test 401 was firstly developed in 1987, which got revised and released in 1992 as fixed dose procedure by taking death of animals as endpoint to calculate LD50 value. In 2002, Instead of waiting for animal to die, they developed certain toxico/pathological signs  as the measure of LD50 calculation. This new method is less painful for tested animals as well as easier for researchers to get data earlier. Till today, Test 420 and 423 are the most commonly used testing methods for determination of LD50 for any chemical. 

 All of these 96 testing methods are available in OECD online library. Click on the following link to get access to them 

https://www.oecd-ilibrary.org/environment/oecd-guidelines-for-the-testing-of-chemicals-section-4-health-effects_20745788
www.oecd.org
https://www.youtube.com/watch?v=9zYqt-iQ4ns

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Internal and External validity in Research

A study suggested that standardized mortality of patients with epileptic disorder in world bank defined HIC (High income countries) is found to be 4 - 15 times greater than that of  low and middle income countries (LMIC); frequent cause of death is reported to be secondary to disease such as drowning, head injury, burn etc. What do you think of this finding ? does it look valid / logical ? Go through the article to get your answer.

Validity is a way of finding out whether or not a test or an experiment accurately measures what it claims to. If a finding of research is having good internal as well as external validity, that is definitely considered strong enough to generate evidence by scientific community. But depending upon the type of research design we chose as well as nature of research itself, there would be unequal distributions in these two validity measures.

Why Does Research Need to be Validated ? 

Fundamental question to be answered is 'what is the objective of our research work ?' We want to test the effectiveness of some new intervention or trying to observe the consequences of any exposure in long run or simply want to make any positive changes in the field. Regardless of the intentions, we have very limited control over the activities we are performing, specially for the studies conducted in human beings. All the research guidelines, SOPs, Protocols, regulatory requirements and scientific appraisals are in place to make sure that our activities are to add something new to knowledge and society by following the current rules and regulations. It Simply means, Validity is needed in every steps. 

What Does Internal Validity Suggests ?

When any causal relationship between the cause and effect is inferenced, internal validity always tells us that result is not influenced by any external factors but research environment is solely accountable for it. In order to claim good internal validity of the research work, procedural aspects of research should be followed without any fail such as correct choice of methodology, protocol adherence, subject selection criteria and data analysis. following the appropriate scientific and regulatory measure controls all the confounding variables,  enhancing the internal validity, also increase the chances being recognized by renowned journals. 

What Is External Validity ? 

It is the extent to which finding of one research can be reproducible in real world. Once Internal validity of the study is assured, then researcher should think of external validity of his work because ultimately intention of any research work to bring about the positive changes in the field. Most of the epidemiological and Psychological studies confront this issue than Interventional studies. Here are the common reasons / examples why any studies with even good internal validity fails to prove external validity and could be misleading if applied.

1. Patient Characteristics: With vast distribution of geography, culture, ethnicity and economic structures, genetic tendency of a individuals responding to a particular trigger may be entirely different from others. Therefore, Incidence and prevalence of a disease or an outcome is different from country to country. Validity of Case control and Cohort studies conducted in a particular country may be  insignificant in other country.
2. Settings: Research setting not only refers to the environment but also technological advancement as well healthcare system of that particular country with equal importance. When studies are conducted based upon the registries and national statistics provided by the government, there is very high chances that real data is being missed; official judgement as well as rules and policies created on the basis of such data could be misleading too. Now apply this concept to above mentioned example. 
3. Time: time affects the people's perceptions, their competency and vulnerability. for example: studying effect of climatic factors in peoples health would not be as relevant 20 years back as it is today. Similarly epidemiological as well as ecological studies conducted in the past lose their external validity over the time and needs to be redefined by conducting much comprehensive studies. 

What If You Are Not Able To Validate Your Study ?

The first problem researcher will face is to publish his work in journals because there would be too much of probing from the reviewer and editors. In this scenario, if internal validity is found to be compromised, that is complete wastage of the resource and time. On the top of that, chances of research participants being affected negatively is very high in poorly conducted study. Such deviated and poor quality data not only be unable to draw any conclusion but also misleading in case got succeeded. 

Few of the methodologically sounding published research Works also carry a potential to be misleading if we do not consider confounding factors behind. In such cases, cross conductance of study and regular update of new information from regulatory authority as well research institutes can help to apply appropriate rules and health policy. 

                                                                 
                                                                                     Thank You !!!

References:

• Patino, C. M., & Ferreira, J. C. (2018). Internal and external validity: can you apply research study results to your patients?. Jornal brasileiro de pneumologia : publicacao oficial da Sociedade Brasileira de Pneumologia e Tisilogia, 44(3), 183. https://doi.org/10.1590/S1806-37562018000000164
• https://onlinelibrary.wiley.com/doi/full/10.1111/epi.13603
• https://www.youtube.com/watch?v=t5bTR-CIeFQ

Does Clinical Trial on Hydroxychloroquine Support the Clinical Practice for COVID-19?

Amid COVID-19 global pandemic, multiple treatment options are tested and recommended by scientific and regulatory authorities followed  by evidence synthesis. Drugs in this list are Dexamethasone, Ramdesivir, Hydroxychlroquine, Chloroquine etc. Among all these globally recommended treatment options, Hydroxychloroquine shows the most contradictory and controversial result. Multiple Clinical Trials are being registered and conducted in various countries including China and US. Recently published comprehensive study on Hydroxychloroquine comparing it's efficacy with standard care completely shattered it's use in management of Coronavius infection. Here, I will be discussing about the evidence based upon the findings of trial conducted in Brazil.

What is Hydroxychloroquine ?

1. HCQ is the hydroxylated form of chloroquine; currently in use to treat various autoimmune diseases like Rheumatoid arthritis (RA), systemic lupus erythematosus(SLE) with much less side effects than Chloroquine. 
2. Structurally similar to it's parent compound Chloroquine, widespread prophylactic medication for Malarial infection. overdose of which causes acute poisoning leading to death. 
3. Because of it's chemical nature, hydroxychloroquine is weak base with immunomodulator property, HCQ was considered as a potent candidate to treat novel corona virus since outspread. 

Promising Pre-Clinical finding

As per the editorial  published in "The Nature" on 18 Mar 2020, Hydroxychloroquine was found to be effective to control SARS-COV-2 infection as per the in-vitro study. During the experimentations, Antiviral effect of HCQ was compared with Chloroquine (HC) for SARS-COV-2 infection  by in-vitro method. Dose response curve was plotted against SARS-COV-2 at four different multiplicities of infections (MOI). Viral RNA copy number was quantified and plotted post infection. 50 % Maximum effective concentration for Hydroxychloroquine was found to be significantly higher than chloroquine against all 4 MOIs. The observed result for effective concentration (EC50) was found to be statistically significant. In same study, significant changes in morphology of Early Endosomes (EEs) and Endolysosomes (ELs) was noticed, which ultimately impacted the transport of virus inside cells and tissues. 

Based upon the evidences like this, few government authorities, Including that of Brazil have approved the use of Chloroquine and Hydroxychlorquine for the management of severe Coronavirus infection. Subsequently, prescription of HCQ has increased post COVID all over the world with record braking mark of   2000% in United State. This overwhelming use was based upon few  clinical and non-clinical data with scant evidence. 

       What Does Recent Clinical Trial Finding Suggest ?

As per the recent publication on New England Journal of Medicine on 23 Jul 2020, there was no clinical improvements in the hospitalized patients with COVID-19 by administration of Hydroxychloroquine with or without Azithromycin on 15 Days as compared to standard care.

Multi-center, randomized, open label, controlled study was conducted in 55 different hospitals in Brazil on 667 patients - 504 confirmed COVID-19 cases where Hydroxychloroquine  was administered either standalone or in combination with Azithromycin for the period of 15 days post hospitalization. One group of patients were administered standard care as control, another two experimental groups with Hydroxychloroquine ((400 mg twice daily) alone and combined with Azithromycin respectively in 1:1:1 ratio. Here, standard care means administration of drugs from glucocorticoids, other immunomodulators, antibiotics and antiviral therapy group, where treating doctor can make their own choice. Clinical status was considered as primary outcome and recorded on following nominal scale. 

1. Not hospitalized with no limitation in activities
2. Not hospitalized with limitation in activities
3. Hospitalized but no oxygen supplementation
4. Hospitalized and providing supplemental oxygen
5. Hospitalized and oxygen supplemented through high flow nasal canula / non-invasive ventilation
6. Hospitalized with mechanical ventilation 
7. Death 

Statistical analysis of this data was performed by Mixed ordinal logistic regression method. Odd's ratio calculation for HCQ + Azithromycin versus control was 0.99, HCQ alone versus control, 1.21 and HCQ + Azithromycin versus HCQ alone was 0.82 with confidence interval of 95%. 

Conclusion

Based upon the finding of above mentioned study, Hydroxychloroquine is not an treatment option for COVID-19 infected patients. Considering few earlier randomized double blind study conducted in United state, Hydroxychloroquine is also not an prophylaxis for COVID-19 infection. 

References

1. Liu, J., Cao, R., Xu, M. et al. Hydroxychloroquine, a less toxic derivative of chloroquine, is effective in inhibiting SARS-CoV-2 infection in vitro. Cell Discov 6, 16 (2020). https://doi.org/10.1038/s41421-020-0156-0
2. https://www.saude.gov.br/noticias/agencia-saude/46601-cloroquina-podera-ser-usada-em-casos-graves-do-coronavirus
3. https://www.nejm.org/doi/full/10.1056/NEJMoa2019014