Le site de vulgarisation scientifique de l’Université de Liège. ULg, Université de Liège

The secrets of female Viagra
2/20/13

Another challenge: the nasal mucous membrane's surface of absorption is very limited, compared with that of the intestinal villi for instance. Hence, we can only administer powerful molecules via this route that are active at very low doses, i.e. micrograms, which is luckily the case for sex hormones. On the other hand, there is no question of administering one gram of paracetamol via the nose!

Every formulation is therefore the result of a compromise between the patient’s comfort, the biopharmaceutical activity, the molecule’s stability, etc. In this case, the challenge was above all to make the molecule soluble in the right excipient, in order to obtain a sufficiently concentrated solution to achieve the therapeutic concentrations – and the desired effect – with just a few microlitres spayed into the nose”, Brigitte Evrard continues.

As for the spray itself – i.e. the device that delivers the product – this is beyond the competences of a pharmaceutical technology laboratory and falls under the scope of another domain: plastics engineering. Companies specialising in the development of drug administration systems are responsible for designing devices according to the desired angle of the spray, the fineness of the drops, etc. Services that are also useful for the development of products intended for administration through inhalation, which is, it would seem, one of the most promising areas according to Brigitte Evrard. “Currently, this route is only used for pulmonary drugs: against asthma, COPD, cystic fibrosis, etc., for topical use. But the lungs could also be used for the systemic administration of drugs because they have the benefit of having a much larger surface of absorption than the nose. Therefore, it’s a very attractive route for a formulator!” she says enthusiastically. A inhalable insulin formukation was briefly marketed a few years ago but was quickly removed from the market (for commercial reasons, apparently, and not because of the method of administration). Today, several phase II and III studies are testing molecules that can’t be administered through the conventional routes, such as peptides, proteins, genetic material, etc. A whole new chapter of pharmaceutical technology looks set to begin in the future (Read the box).

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