39 Drug Surveillance

Howard J. DreskinandWin M. Castle

The primary duty of a drug monitoring system is
less to demonstrate dangers or to estimate inci-
dences than to initiate suspicions...(Finney, 1982)
Drug safety monitoring is relevant to a wide
audience (e.g. patients, prescribers, regulators
and lawyers). Patients gain most from enhanced
prescribing information or removal of products no
longer considered to be safe, as a result of pharma-
covigilance by companies and regulatory agencies.
Prescribers benefit by being able to prescribe the
most appropriate medicine for a given patient.
Regulators continuously watch over the adverse
events reported by manufacturers and independent
reporters, add newly reported events to existing
safety databases for analysis, and are often in a
position to make comparisons between different
members of the same pharmacological class. Law-
yers both within companies and in the litigation
bar, are interested in whether the local prescribing
information is up to date as far as adverse event
reporting is concerned.
On the supply side, safety monitoring is a shared
responsibility. Monitoring the safety of medicines
is a shared responsibility involving, among others,
the pharmaceutical industry, physicians and regu-
latory authorities. The primary responsibility must
belong to the individual pharmaceutical company,
which knows the most about the drugs and has the

greatest interest in the proper and safe use of the

drugs and in maximizing the usefulness of their

products to patients.

Pharmacovigilance is the name of the art, science

and tools to identify new adverse events or safety

signals. Manufacturers need to analyze adverse

events both individually and in aggregate fashion.

Pharmacovigilance can be formalized as periodic

safety update reports,ad hocincreased frequency

reports, scientific publications and other types of

safety analysis. Most countries also require forma-

lized reporting of serious adverse drug reactions

(ADRs) and aggregate periodic safety update

reports to regulatory authorities. There are many

hurdles to overcome, as history shows.

For both the creators and the users of this infor-

mation, the passing to signal from noise is crucial.

Useful clinical information must always be dis-

closed, but optimally this should not be amongst

heaps of the irrelevant because that, too, will fail to

communicate useful information.

39.1 Reasons for monitoring

safety post-marketing

The safety profile of a drug is only at an early stage

of evolution when the NDA/PLA is approved, and

Principles and Practice of Pharmaceutical Medicine, 2nd Edition Edited by L. D. Edwards, A. J. Fletcher, A. W. Fox and P. D. Stonier
#2007 John Wiley & Sons, Ltd ISBN: 978-0-470-09313-9