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

International Journal of Research in Pharmaceutical and Biomedical Sciences ISSN: 2229-3701
No scope for picking up chronic or delayed ADRs.
DISCUSSION
ADRs significantly diminish quality of life, increase hospitalizations, prolong hospital stay and increase
mortality [Pirmohamed M, et al, 2004]. The financial cost of ADRs to health care systems is enormous.
There are several recent trends that are likely to expose more people to ADRs. For example, new drugs are
being approved for marketing more quickly and without adequate long-term safety studies, supranational
marketing is making drugs available to many more people at an early stage, and removal of restrictions on
availability is leading to some medicines being used more widely by patients for self-medication.
Monitoring of ADRs or pharmacovigilance is a new and evolving science [WHO, 2006]. Although
various strategies and systems are being used worldwide, in general, most suffer from problems of
underdetection and / or underreporting. Therefore the exact incidence (either population- or prescriptionbased)
of specific ADRs is unknown. Information about ADRs from the pharmaceutical industry and
regulatory authorities is usually not accessible to the public. Health professionals’ motivation for
pharmacovigilance is low, there is little encouragement for them to be involved in the process. Patients
receive inadequate and poorly understandable information about ADRs. Reports directly from patients, the
individuals who actually suffer the consequences of ADRs, are often not conveyed by health professionals
to established monitoring centers or to the regulatory authority. Added to this, is the difficulty in causality
analysis of ADRs which often discourages health professionals from reporting [Karch FE & Lasagna L,
1975].
In this context, it was felt that focusing on pharmacovigilance is the need of the hour [WHO, 2004]. The
field of cancer chemotherapy was selected because this is one therapeutic area where ADRs are likely to
occur frequently, if not universally [Iyer L & Ratain MJ, 1998]. Surprisingly, our literature survey revealed
dearth of reports on ADR profiles in cancer chemotherapy. Although individual case reports are there, few
focused studies were encountered [Shepherd GM, 2003]. The situation is even more serious in the Indian
context [Kshirsagar NA, 1993]. A medline search with a last 10 years limit revealed no published Indian
study of ADR profiling of anticancer drugs.
The ADR prevalence encountered suggest that practically all patients receiving cytotoxic drugs suffer one
or more ADRs. The spectrum of drugs encountered is typical of a medical oncology unit subjecting patients
to various combination chemotherapy regimens. However, the percentage figures indicating involvement of
individual drugs in adverse events has to be interpreted with caution since it may simply be dependent on
the frequency of usage of the drug. Thus, cisplatin being the most frequently incriminated drug does not
necessarily mean that it is the one most prone to cause ADRs; it may reflect the fact that cisplatin is one of
the most widely used anticancer drugs in that unit. It may be noted that none of the patients surveyed were
on interferons or other types of biological response modifier drugs.
The overall profile of ADRs encountered is also typical of the acute treatment-emergent adverse events
likely to be encountered in a medical oncology unit. Expectedly, nausea with or without vomiting, was the
most common event. However, it has already been mentioned that one of the limitations of this study was
the inability to monitor patients serially, since patients were admitted, received their chemotherapy and
were discharged in 1 or 2 days. Thus no attempt was made to detect events like peripheral neuropathy or
neutropenia which requires serial monitoring of the patient, either clinically or through laboratory tests.
Even in instances like gum bleeding, which suggests underlying laboratory abnormalities like reduced
platelet count, there was no scope of recalling the patients for review of their test records. Only a few
patients admitted for repeat cycle therapy could be linked to previous cycles. The spectrum of ADRs
encountered for individual drugs also matched their known ADR profiles and there were no surprising
events. In the 3-month span of the study it was not reasonable to expect detection of chronic or delayed
ADRs like doxorubicin-induced cardiomyopathy.
The other limitation of the study was the inability to obtain full-time support of the oncologists in the
monitoring activity, despite their best intentions. This is needed to understand the ADR in the context of the
patient’s history and clinical examination and distinguish it from the symptomatology produced by disease
or other drugs. In fact the team approach works best in focused or intensive monitoring[WHO, 2004] and
the physicians’ enormous routine workload meant that the team in our case was less than optimum.
Pharmacovigilance is an arm of patient care. It aims at making the best use of medicines for the treatment
or prevention of disease. No one wants to harm patients, but unfortunately any medicine will sometimes do
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