Main modes of drug action

This posts provide a very simple overview of the main modes of actions of drugs. There are three ways in which they work:

Replacing chemicals that are deficient.
Interfering with cell function.
Acting against invading organisms or abnormal cells.

These are now described in a little more detail.

Replacing chemicals that are deficient.

Here chemicals are added that are not being obtained by the normal eating or functioning of the body. This include hormone treatment and use of vitamins to deal with rickets or scurvy or even iron to deal with anaemia.

Interfering with cell function.

Here drugs work by affecting cell function. This includes controlling pain and inflammation and can also causes cells to either increase or decrease in activity.

If a medicine intensifies cell activity it is called an AGONIST.

If a medicine reduces cell activity it is called an ANTAGONIST.

Many medicines work by interfering with enzymes (biochemical catalysts) produced from cells by increasing or reducing their activity.

Acting against invading organisms or abnormal cells.

Here drugs work by treating infection, such as bacterial or fungal infection, as well as the treatment of cancer.

For more information on our on-line training courses on how medicines work – please contact us.

I hope this is of interest. Dominic

Annex 1 has finally arrived, 25th Aug 2022 saw the publication of Annex 1. Normally, updates to GMP chapters and Annexes have a 6-month lead time for implementation. In the case of the new Annex 1, the lead time is 12 months, except for clause 8.123 relating to lyophilization which has 24 months lead time.

Annex 1 was first issued in 1971 as the only annex in the first ever UK guide to Good Manufacturing Practice. Since then, there have been several updates but not full revisions. In 2012 there was a proposal to revise Annex 1 with a re-proposal in 2014 by the UK’s MHRA. At the time, a full rewrite was considered unlikely and instead the intention was to provide a document that would confirm regulatory expectation and as such, not place any new requirements or costs on the pharmaceutical industry.

While this principle, is still upheld, it was clear from the first draft for public comment of December 2017, that a rewrite was being undertaken. The first draft created around 6200 comments coming from regulatory organizations, such as the pharmaceutical cooperation scheme, regulatory bodies outside of the EU, support organizations such as the Parenteral Drug Association, the Parenteral and Healthcare Sciences Society, the Pharmaceutical Microbiology Interest group as well as representatives from the manufacturers within the pharmaceutical industry to name just a few. Rarely do updates require a second public consultation but in the case of the annex 1 update a second draft was issued in March 2020 although this was a more targeted review in terms of the sections and clauses that comment was being sought for.

About the author

Andy Martin

Andy started working in the Pharmaceutical industry in 1985 as a lab technician for Smith & Nephew. Following this he had a number of roles culminating when he took over as QA Microbiology Manager. In 2003 he moved into Pharmaceutical Training and then in 2007 he moved back into Microbiology when he took up the position of Microbiology Manager for Catalent Pharma Solutions. Since 2012 he has operated as a consultant specialising in Microbiology and Quality Systems.

Training courses on Annex 1

There are a number of half-day workshops organised to take you through the changes in more detail and to look at how they relate to your organisation.

More details