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Transdermal meaning through the skin™ is a route of medicine administration to deliver a specific dose of medication through the skin and into the bloodstream e.g. transdermal patches or ointments. Examples include nicotine patches and scopolamine patches for motion sickness.


Transfer of blood or blood components (red and white blood cells, plasma, clotting factors, or platelets) into the bloodstream intravenously.


A transgenic organism (otherwise known as a genetically modified organism (GMO)) is an organism whose genetic material has been altered. Genetic modifications are made to produce certain traits (such as disease resistance in crops) or to cause the organism to produce specific biological products (for example, bacteria have been altered in order to produce insulin for diabetes treatment, and plants have been altered to make antibodies for blood-clotting factors).

Transgenic organisms are used in the production of medicines, in new forms of medicine such as gene therapy, and in agriculture.

Genetic modification is also a useful tool for scientists in many areas of research, including those who study the mechanisms of human and other diseases.


In the field of genetics, translation is the process by which a protein is made from messenger RNA (mRNA). During translation, an RNA sequence is read and translated into the code of amino acids, which are the building blocks of proteins.

Treatment Emergent Adverse Event

Treatment emergent adverse events (TEAE) are undesirable events not present prior to medical treatment, or an already present event that worsens either in intensity or frequency following the treatment.

In medicines development terminology, an adverse event (AE) is any undesirable event that occurs after a participant officially consents to take part in a trial (and could occur before treatment begins). An adverse event may or may not be associated with the medicine under investigation, but must be documented because it happened during the trial period.

A treatment emergent adverse event (TEAE) is an adverse event that occurs only once treatment has started.

Treatment group

In a clinical trial, the treatment group (as opposed to the control group) usually refers to the group of participants that receives the treatment under investigation. The treatment group is also known as the treatment arm™.

Trial arm

A trial arm is a group of participants that receives the same interventions, or no intervention, according to the study protocol. Many randomised trials have two arms, but some may have three or even more. This is decided before the trial begins.

Trials with several arms (multi-arm) allow more than one treatment to be tested at once, and can reduce the costs and time needed during clinical development. Multi-arm, multi-stage (MAMS) trials take this idea a step further and allow the recruitment of participants in a particular arm to be stopped partway through if that treatment is not producing satisfactory results. MAMS can also allow for new treatments to be added to the trial as they become ready for testing.

Type I Error

Type I Error occurs in statistical hypothesis testing when a null hypothesis, which is actually true, is incorrectly rejected. Type I errors are also known as 'false positives' they are the detection of a positive effect where no effect actually exists.

As a stark example, Type I errors could kill a patient - for instance, if a study incorrectly found that the standard of care was not better than the new treatment, and consequently the new treatment was given to patients, the results may be catastrophic.

Type I errors cannot be completely avoided, but researchers should decide on an acceptable level of risk of Type I error when designing clinical trials. A number of statistical methods can be used to control the Type I error rate. The methods to be sued in a clinical trial should be detailed in the study protocol or the statistical analysis plan for that trial.

Type II Error

Type II Error occurs in statistical hypothesis testing when the null hypothesis is incorrectly accepted. Type II errors are also known as 'false negatives' they are the failure to detect a positive effect where the effect does exist.

Type II errors mean that potentially valuable research goes to waste. As no positive effect is detected, research may be halted. This research may have been useful, but as no further study takes place, no harm is done to patients.

Type II errors cannot be completely avoided, but researchers should decide on an acceptable level of risk of Type II error when designing clinical trials. To reduce the risk of Type II errors to acceptable levels, the power or sample size (the number of participants in a study) can be increased.

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