Birth of a drug
Birth of a drug

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Birth of a drug

5.2 The pharmaceutical background

The existence of alpha receptors had been known for many years, and the obvious approach of trying to block these receptors, and hence prevent the noradrenaline from binding, had already been tried by many research groups. A number of compounds with alpha-blocking activity had been identified, including one called prazosin (2) discovered by Pfizer at their US research laboratories in Groton. Substances such as prazosin which block agonist action are called antagonists.

However, none of the early alpha-blockers, with the single exception of prazosin, reduced blood pressure other than transiently; furthermore, the old alpha-blockers usually displayed undesirable side-effects. Prazosin, on the other hand, was shown to be effective at lowering blood pressure and safe in toxicological evaluation, and so in due course was made available for the treatment of hypertension.

Prazosin needed to be taken two or three times a day, whereas, as indicated earlier, a once-daily therapy would be preferable for the treatment of a chronic condition such as hypertension; furthermore, the lack of detailed understanding of the mechanism of action of prazosin (in other words, the answer to the question: why was it effective where other alpha-blockers were not?) was a significant limitation to implementing a rational follow-up programme and, after some initial work, research in this area was discontinued.

S344_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus