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Drug - The long road to drug

Apr 9th 2015 at 10:55 PM

The search for new drugs against certain diseases or conditions is slow and does not always end with a success. From 5,000 to 10,000 hopefuls that will be tested in the research laboratories of pharmaceutical companies, lands on average only one as a finished medicine at the pharmacy. And in between there are usually more than ten years.

Search for the "Target"

Even before tests are made with new materials, consider the researchers, which features the sought substance have or what reaction he should be triggered in a diseased body, such as a reduction in blood pressure, the blocking of a particular neurotransmitter or the secretion of hormones. The researchers are looking for a suitable "target", ie an attack in the diseas process, where scheduling a drug and may affect the disease process low. In most cases enzymes, receptors serve (docking sites on cells), and other proteins as targets.

Search for the active substance

Once a target is established after a suitable drug gefahndet (screening). For employees in research laboratories, this means primarily: Test, test, test. Use of robots can be studied up to 300,000 different substances for their suitability per day. Of which shows approximately every 200 to 1000. Substance actually has an effect on the selected target, although sometimes only a very small.


In most cases, these "hits" or "hits" have yet to be optimized. Sometimes you can increase the effectiveness of a substance, for example, if its structure is slightly changed. In these experiments, scientists often work with computer simulations that help can be estimated the effect of a chemical change in the substance in advance. The prognosis is good; the substance is therefore modified in real, in the laboratory. Subsequently, their effect is examined at the target again. In this way, the researchers gradually improve their drug candidates until they think that he is ready for the pre-clinical studies.

Preclinical studies

They are performed on cell cultures and animals and to clarify what happens to the drug candidate in the body:

How is it received?

• How it is distributed in the body?

• What kind of reaction it triggers?

• Will he converted or degraded?

• When he retired?

It also examines exactly what effect the substance on the target exercises how long this lasts and what does is necessary. Also on possible side effects is respected. The preclinical also serves to check the safety of the substance. Many fail at this hurdle, because they prove, for example, as toxic, harmful to an embryo or fetus or carcinogenic. Only substances that have passed all safety inspections, tests must pass through to humans (clinical trials).

Phase I trials

The drug is tested on humans for the first time. The aim is to confirm existing findings from the tests in vitro and in animals. The test subjects usually serve 60 to 80 healthy adults who have volunteered for it. You are first administered only a small amount of active ingredient. In up to 30 consecutive studies will examine whether the active substance in the body actually behaving as it may be presumed that preclinical testing. Before each study an independent ethics commission (composed of physicians, lawyers, theologians and laymen) to give their consent.

Tablet, spray or ointment?

After successful completion of Phase I, the Galenic comes into play, that is, the scientists tinkering now "packaging" at the optimum for the active ingredient:

Should he be given better as a tablet, capsule, suppository or injection? An important question that depends on many things - the dosage form determines how reliable, how fast and how long the drug can do its job. It also affects the nature and severity of side effects. So some active ingredients are as syringe much better tolerated than when they come in tablet form through the gastrointestinal tract into the body.

Phase II and Phase III studies After the healthy volunteers in Phase I are now for the first time ill turn.

Phase II, the new drug candidate at most 100 to 500 patients will be tested. The focus is on the efficacy, optimal dosage and tolerability of the drug. The same is reviewed in Phase III - only this time on a lot more patients (several thousand).

Addition of the attention to possible drug interactions. In both phases, each with different treatments are compared: Only a proportion of patients receiving the new drug, the rest either take their usual standard drug or a placebo - a drug that looks exactly like the new, but contains no active ingredient. As a rule, know neither the patient nor the doctor who gets what. Such "double-blind studies" are intended to prevent hopes or fears among patients influence the outcome of treatment. Since 2007, each new drug is in Phase II and III trials must also be tested against minors in Europe when it against a disease is addressed, which also occurs in this age group. Prior to those new drugs were almost exclusively tested only in adults. The tests in children or adolescents are usually initiated only when the phase III trials have been completed successfully in adults.


Even if a new drug has passed all tests, it cannot simply be sold so. The manufacturer must first submit a paid application to regulatory authorities, and then grant him after considering all the study results in the best case, the approval for sale. But that takes time - on average takes the authorization process in Europe and half years.  There is also the possibility of approval for a new drug with national authorities and thus to apply only in the country concerned. In Germany, the Federal Institute for Drugs and Medical Devices (BfArM) and the Paul Ehrlich Institute (PEI) are responsible for: applications for human medicines are filed with the BfArM; the PEI takes care of sera, vaccines, test allergens, test sera and test antigens, blood and blood products, tissue, and drugs for gene therapy and cell therapy.

Phase IV

Even after the approval authorities and pharmaceutical company keep the new drug in the eye, for example with regard to rare side effects. These are undesirable effects which occur in less than 1 in 10,000 patients and therefore hardly in the previous study phases (with smaller patient groups) can be detected. In protocols doctors also hold as proven the new drug in everyday life in their patients.

The results of such observations application use the manufacturer, for example, to improve the strength or dosage form of the drug on. Sometimes seen in everyday practice and that the drug still helps against other diseases. The manufacturer can then further research in this direction and apply for success for this new indication approval. But there are also cases where it turns to the time that the application of a drug is associated with unforeseen unacceptable risks. The authorities may specimen will then withdraw approval or the manufacturer accepts it voluntarily from the market.

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