The role of chemical agents and pharmaceautical drugs (medications) in the production of birth defect, congenital malformation and/or congenital anomaly in humans is difficult to assess.
Relatively few of the many drugs used during pregnancy have been positively identified as being teratogenic e.g thalidomide, an antinauseant and sleeping pill.
WHY?
This is due to the practical inability of drug researchers to try novel drugs on pregnant women as this is against regulatory polices… Furthermore in phase 4 trials( when the drug is in the market) doctors do not often report cases of adverse drug reaction to central monitoring bodies so the drug goes unchecked. This is my opinion
It is true that novel drugs cannot be tried on pregnant women due to regulatory polices. Critically analysing the sentences in the question, you would realise the question didn’t make reference to novel drugs but pharmaceutical products in general.
For clarity purposes, what are clinical trials and why are they conducted?
Clinical trials are conducted with two main objectives in mind;
1. To test the efficacy or efficiency of a novel drug, treatment/surgical procedure, medical equipment, etc
2. To test for the safety
Important regulations guide the process of clinical trials to ensure the most suitable test results as well as due to ethical considerations. Such regulations prohibits trials to be conducted on;
1. The old (>55 years) as they consume alot of medications due to underlying ailments that comes with age
2. Children and individuals with unrelated ailments. The trials have to be targeted or exclusive as you cannot try a cancer drug on a DM patient
3. Pregnant women due to potential risk the drug may have on the developing fetus.
Clinical trials generally ensures an option of a better therapeutic treatment plan for patients if they turn out to be a success and are usually done in stages i.e 0-IV.
Thank you.
This is because the drug and other drugs too, interferes with the signalling pathways involved during the period of organogenesis (4th-8th week) of an embryo, especially that of the limbs leading to meromelia, amelia, phocomelia etc, it also affects other organs leading to heart, urinary system, ear and facial defects etc.
It is true that thalidomide interferes with
the signalling pathways during the period of organogenesis and as such, it is a known teratogen. But you cannot say so for other drugs until proven otherwise.
Thalidomide was found to cause limb malformation in children whose mothers ingested the drug early in pregnancy during the 1960’s.
The question was;
What led to this positive correlation of thalidomide and teratogenicity?
Thank you
Teratogens are substances that may cause birth defects via a toxic effect on an embryo or fetus. Thalidomide is one of the taratogenic substance,Thalidomide causes birth defects. people using the drug should be advised of the risks and avoided in pregnancy; this applies to both men and women, as the drug can be transmitted in semen.
It is great that you decided to reiterate the message passed across in the question for the purpose of emphasis.
It is true that both sex (male and female) utilizes thalidomide as the therapeutic effect of the drug isn’t only for the purpose of nausea and sleep.
Thalidomide is also an immuno-regulatory product as it is used in the treatment of HIV and other immuno compromising conditions.
Can the drug be transmitted via semen?
I am just hearing of this for the first time but I seriously doubt the genuineness/accuracy of that statement.
Thank you
I believe scientists are yet to assess some chemical agents / drugs because of the unavailability of embryos to test on. Testing the effects of drugs on embryos will require them to perform prematured abortions.
And those who will intentionally leave their unborn babies for experiments are hard to come by.
That is my take on why it is difficult to assess the role of some drugs in anomaly.
Firstly, an embryo is a developing human within the period of 3rd- 8th week and during this period, most of the organs are preformed.
To assess the role of a drug in the body of a human, you must understand the pharmacodynamics and pharmacokinetics of the drug i.e what the drug does to the body and what the body does to the drug respectively.
To do this, the human must be alive i.e living and not dead.
To abort a baby simply means to terminate the life of a human. If the life of the developing human is thus terminated, how do you intend to run clinical trials or drug test on the human?
Thank you
Truth,thank you for the reply.
Well in my opinion the reason is because most drugs are not allowed to be used do clinical test on pregnant women..Also it is mostly in the 3rd-8th week during organogenesis that a drug can cause malformation so to monitor the effect of drugs during this periods is quite strenuous…. Even during pregnancy so women Vomit this reduces the concentration of the drugs that reaches the child and also increase in plasma level so it is quite difficult because this physiological changes affects the pharmacokinetics of the drugs
No stage of development is completely safe.
Whereas most abnormalities are produced during organogenesis, defects may also be induced before or after this period.
Also, I must State for the purpose of emphasis that unfortunately, most women do not appear for their first prenatal visit until the eighth week, which is after the critical time for the prevention of most birth defects.
Thank you
Because they cause severe limb defects such as Amelia and Meromilia
True but this doesn’t answer the question;
What led to this positive correlation of thalidomide and teratogenicity?
I think the drugs used by a pregnant woman during her gestational period can be many,so it’s quite difficult to extract enough information about them from her to predict their safety,and also,the time she was exposed to chemical agents matters,she might be able to give less information on this as well
Hello Ulna bursitis☠️🦴
I am indeed pleased with your answer as your thoughts are correct.
You have successfully answered the first part of the question (paragraph one).
Kindly scroll below to see a more comprehensive answer from us on both aspects of the question.
Thank you for attempting today’s review question.
Warm regards
Most teratogenic assays are done via embryological studies on rats or mice and it is difficult to carry out human trials because pregnant volunteers for clinical trials will be almost impossible to find… While it is true that the preclinical trials give a glimpse of the expected outcome in humans.. It does not completely tell for sure that same effect (teratogenic) would be seen in humans because it was seen in mice and due to specie differences. After teratogenic effect seen with thalidomide administration as antiemetic during pregnancy, serious restrictions and regulations were also placed on other drug candidates to be used during pregnancy. Basically one cannot specifically predict the effect of drugs on the embryo because clinical trials are rarely done on pregnant women
Hello Faith Shulamite🥰😍
I am indeed pleased with your response.
You have successfully answered the first part of the question (paragraph one). Indeed, the discovery of the teratogenicity of thalidomide was revolutionary and led directly to the science of teratology and founding of the teratology society.
Thank you for attempting today’s Review Question.
Warm regards
The role of chemical agents and pharmaceutical drugs in the production of abnormalities in humans is difficult to assess for two reasons;
1. Most studies are retrospective, relying on the mother’s memory for a history of exposure, and
2. Pregnant women take a large number of medications.
On the other hand, relatively few of the many drugs used during pregnancy have been positively identified as being teratogenic because they may produce a note common type of malformation such as cleft lip or heart malformation and thus the association of the drug might easily have been overlooked.
The causal relation of thalidomide and meromelia was discovered only because the drug produced such an unusual abnormality.