Monitoring of Suspected Adverse Drug Reactions in Oncology Unit ...

International Journal of Research in Pharmaceutical and Biomedical Sciences ISSN: 2229-3701
drug’s known pharmacology. Examples include hemolysis with methyldopa, or thrombocytopenia with
angiotensin converting enzyme inhibitors. Continuous post-marketing surveillance is often required before
many Type B reactions can be identified. They are generally due to hypersensitivity or identified
‘idiosyncratic’ mechanisms.
Adverse drug reactions (ADRs) are not so silent threat to the health of a nation. During the last decade it
has been demonstrated by a number of studies that medicine induced morbidity and mortality is one of the
major public health problems. With the quantal leap in the number of drugs being marketed it is becoming
increasingly important to monitor ADRs. Worldwide, efforts are ongoing to identify ADRs, monitor drug
use and improve prescribing habits of practitioners to ultimately make use of medicines safer.
It has been estimated that ADRs are 4th to 6th largest cause of mortality in the USA [Lazarou J et al,
1998]. They contribute to the death of several thousands patients each year, and many more suffers from
their ADRs [Kelly WN, 2001; Somberg JC, 1998]. The percentage of hospital patients suffering ADRs, in
some surveys, is more than 10% e.g. Switzerland 17%, France 14.7%, etc.[Vervloet D & Durham S, 1998].
ADRs often impose a high financial burden on healthcare due to hospitalization of patients with drug
related problems. Some countries spend up to 15 to 20% of their hospital budget dealing with drug
complications [Gautier S, 2003].
Unfortunately, there is very limited information available on ADRs in a developing country like India.
Knowledge about ADR monitoring and reporting is lacking among health professionals in India. The
reasons may be multiple – not sure about causality, considered too trivial or common to report, not aware
of the procedure to report, not aware of whom to report. The problem is aggravated by lack of adequate
enforcement of legislation, large number of substandard and counterfeit products circulating in the market,
and lack of access to independent sources of drug information. Thus, one may expect that the burden of
ADRs, both medically and financially, is worse than in the developed countries.
In this scenario, the Government of India has launched a National Pharmacovigilance Programme
(NPVP) in November, 2004 [Bavdekar SB & Karande S, 2006]. The programme mission is to sensitize
medical professionals to the concept and practice of ADR reporting. The operation has countrywide
coverage through 2 zonal, 5 regional and several peripheral centers. Data is collected in the form of
spontaneous ADR reports generated by physicians, either as treatment emergent symptoms complained of
by the patient or signs detected during clinical examination. In addition to untoward medical events, any
abnormal laboratory finding occurring during administration of the drug is also captured. However, reports
collected are not necessarily causally related to the drug with certainty.
Against this backdrop, the current project work was conceived to monitor suspected ADRs with
anticancer drugs, a therapeutic category prone to ADRs, in a focused manner and contribute to the overall
knowledge base regarding ADRs in the country. The work was carried out in collaboration with an institute
already engaged in ADR monitoring as part of the NPVP.
Terminology of adverse drug reactions [Vervloet D & Durham S, 1998]
As mentioned in the introduction, an adverse reaction to a drug has been defined as any noxious or
unintended reaction to a drug that is administered in standard doses by the proper route for the purpose of
prophylaxis, diagnosis, or treatment. Some drug reactions may occur in every one, whereas others occur
only in susceptible patients.
Some other relevant terminology in vogue in this connection is:
Drug overdose : Toxic reactions linked to excess dose or impaired excretion or to both.
Drug side effect : Unintended, usually undesirable, pharmacological effect at recommended doses.
Drug intolerance : Reactions that occur only in susceptible subjects; a low threshold to the normal
pharmacological action of a drug.
Drug idiosyncrasy : A genetically determined, qualitatively abnormal reaction to a drug related usually
to a metabolic or enzyme deficiency.
Drug allergy : An immunologically mediated reaction, characterized by specificity and transferability
by antibodies or lymphocytes, and recurrence on re-exposure.
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