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

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International Journal of Research in Pharmaceutical and Biomedical Sciences ISSN: 2229-3701 e.g. Fetal hydantoin syndrome and phenytoin. Types of allergic reactions [Guglielmi L, et al, 2006; Gruchalla R, 2000] Type I Immediate, anaphylactic. e.g. Anaphylaxis with penicillins. Type II : Antibody (IgG, IgM) dependent cellular toxicity. e.g. Methyldopa and hemolytic anemia. Type III : Serum sickness type; mediated by deposition of antigen antibody complex. e.g. Procainamide and drug-induced lupus. Type IV : Delayed hypersensitivity type. e.g. Contact dermatitis. Serious adverse drug reaction [Knowles S & Shapiro L, 1997] Any adverse experience that results in one of the following outcomes: death, a life-threatening experience, in-patient hospitalization or prolongation of existing hospitalization, a persistent or significant disability/incapacity, or a congenital anomaly/birth defect. Important medical events that may not result in death, be life-threatening or require hospitalization may be considered as serious adverse event when, based upon appropriate medical judgment, they may jeopardize the subject and may require intervention to prevent one of the outcomes listed. Delayed adverse effects of drugs A number of adverse effects may only become apparent after long-term treatment, such as the relatively harmless melanin deposits in the lens and cornea that are seen after years of phenothiazine treatment (and which should be distinguished from pigmentary retinopathy). Other examples include the development of vaginal carcinoma in the daughters of women given diethylstilbestrol during pregnancy for the treatment of threatened abortion; and immunosuppressives and chemotherapeutic agents which can induce malignancies that may not be apparent until years after treatment has been given. Adverse effects associated with drug withdrawal Some drugs cause symptoms when treatment is stopped abruptly, for example the benzodiazepine withdrawal syndrome, rebound hypertension following discontinuation of antihypertensives such as clonidine, and the acute adrenal insufficiency that may be precipitated by the abrupt withdrawal of corticosteroids. These are all Type A reactions. Common therapeutic groups causing adverse drug reactions These are as follows: • Antibiotics • Antineoplastics • Anticoagulants • Antiarrythmics • Oral hypoglycemics • Antihypertensives • Non-steroidal anti-inflammatory drugs (NSAIDs) / Analgesics Vol. 1 (2) Oct – Dec 2010 www.ijrpbsonline.com 4
International Journal of Research in Pharmaceutical and Biomedical Sciences ISSN: 2229-3701 • Diagnostic agents • CNS drugs It has been estimated that the above types account for 69% of fatal ADRs. Body systems commonly involved in adverse drug reactions These are as follows: • Hematologic • Central nervous system • Dermatologic (Allergic reactions in particular) • Metabolic • Cardiovascular • Gastrointestinal • Renal/Genitourinary • Respiratory Detection and monitoring of adverse drug reactions [Gough S, 2005; Atuah KN, et al, 2004; Klepper MJ, 2004; Bates DW, et al, 2003; Arnaiz JA, et al, 2001; Evans JM and MacDonald TM, 1999; Meyboom RH, 1997; Wood L and Martinez C, 1994] By the time a drug is marketed it will usually have been given to an average of 2500 people, and it is likely that clinical trials will have picked up the most common ADRs. It is unlikely that Type B reactions with an incidence of 1 in 500 or less, will have been identified by the time a drug becomes available for widespread use. It is only after much wider use that rare reactions, or those which occur predominantly in certain subgroups within the populations, such as the elderly, are detected, and it is therefore essential to monitor safety once a drug has been marketed. Pharmacovigilance is defined as the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other possible drug-related problems’ [WHO, 2006]. Various strategies of pharmacovigilance include: Case reports and case series The publication of single case reports, or case series, of ADRs in the medical literature is an important means of detecting new and serious reactions, particularly Type B reactions. Case reports have, in the past, been vital in alerting the medical profession to several serious adverse reactions. Examples include oculomucocutaneous syndrome associated with practolol, and halothane induced hepatitis. Case-control studies Case control studies compare drug usage in a group of patients with a particular disease with use amongst a matched control group who are similar in potentially confounding factors, but who do not have the disease. Examples of associations that have been established by case control studies are Reye’s syndrome and aspirin, and the relationship between maternal diethylstilbestrol ingestion and vaginal adenocarcinoma in female offspring. The case control method is an effective means for confirming whether or not a drug causes a given reaction once a suspicion has been raised. Cohort studies Cohort studies are prospective studies which study the fate of a large group of patients taking a particular drug. Cohort studies include ad hoc investigations set up to investigate specific problems (often sponsored by pharmaceutical companies), prescription event monitoring and a variety of record linkage schemes. Vol. 1 (2) Oct – Dec 2010 www.ijrpbsonline.com 5
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