It may be helpful to look at the chemistry of a new drug. Comparing the chemical structure of a new drug with existing drugs may help give an impression of what kind of effects may evolve. This comparison should not be limited to drugs which are marketed for the same indication. (See Box 8.12 for examples).
Box 8.12 Examples of how a drug’s chemical structure can explain its effects
Example 1. In 1990/91 torsade de pointes was reported in connection with the urinary incontinence drug terodiline.
The German bulletin arznei-telegramm realised that terodiline was chemically very close to the antiarrhythmic drug prenylamine which had been withdrawn from the market 10 years earlier because of fatal arrhythmias. After publication of the similarity in the drug structures and the suspicion of parallel adverse effects (arznei-telegramm 1991; no 8: 65) the company withdrew terodiline from the market immediately (arznei-telegramm 1991; no.9: 79). The manufacturer had not been aware of the chemical affinity of the two drugs before this.
Example 2. Atomoxetine is now approved for attention deficit hyperactivity disorder. It had previously been in clinical tests under the International Nonproprietary Name tomoxetine as an antidepressant drug. Atomoxetine has a lot of similarities in chemical structure with serotonin re-uptake inhibitors, like fluoxetine. This may help in understanding and assessing some of the adverse drug reactions, such as aggressive behaviour, which is seen with both drugs [arznei-telegramm 2005; 36: 33-4.].
Contributed by Wolfgang Becker-Brueser, arznei-telegramm, Germany