Canadian Adverse Reaction Newsletter, Volume 22 - Issue 4 - October 2012
Cat no H42-4/1-22-4E
Health Products and Food Branch
Marketed Health Products Directorate
Canadian Adverse Reaction Newsletter Editorial Team
In this Issue:
This quarterly publication alerts health professionals to potential signals detected through the review of case reports submitted to Health Canada. It is a useful mechanism to stimulate adverse reaction reporting as well as to disseminate information on suspected adverse reactions to health products occurring in humans before comprehensive risk-benefit evaluations and regulatory decisions are undertaken. The continuous evaluation of health product safety profiles depends on the quality of your reports.
Reporting Adverse Reactions
Canada Vigilance Program
For more information on how to report an adverse reaction, visit the Reporting Adverse Reactions to Drugs and Other Health Products page.
Caveat: Adverse reactions (ARs) to health products are considered to be suspicions, as a definite causal association often cannot be determined. Spontaneous reports of ARs cannot be used to estimate the incidence of ARs because ARs remain underreported and patient exposure is unknown.
Lyme disease test kits and limitations
- Serologic test results are supplemental to the clinical diagnosis of Lyme disease and should not be the primary basis for making diagnostic or treatment decisions.
- Lyme disease test kits have sensitivity and specificity limitations.
- Health care professionals should be aware of these limitations and are encouraged to report suspected incidents, including false-positive and false-negative results, to Health Canada.
Lyme disease test kits are class II (IV being the highest risk class) in vitro diagnostic devices. The devices are intended for the detection of antibodies to Borrelia burgdorferi in human serum, plasma or cerebrospinal fluid.Footnote 1 They are used to provide serologic evidence of B. burgdorferi exposure.Footnote 1 Infection can result in dermatologic, neurologic, cardiac and musculoskeletal disorders.Footnote 2 Serologic testing is the only standardized type of laboratory investigation available to support the clinical diagnosis of Lyme disease in North America.Footnote 3 The public health agencies of Canada and the United States recommend a two-tiered approach for blood testing when Lyme disease is suspected.Footnote 3,Footnote 4,Footnote 5,Footnote 6,Footnote 7 The first tier consists of an enzyme immunoassay, such as an enzyme-linked immunosorbent assay (ELISA), or an indirect immunofluorescent assay. If the result of first-tier testing is negative, the sample is reported to be negative for antibodies to B. burgdorferi and is not tested further. If the result is positive or indeterminate, second-tier testing with a standardized Western blot is then performed.Footnote 3,Footnote 4,Footnote 5
As of June 2012, Health Canada received one incident report of false-negative serologic test results for 24 patients that may have delayed treatment. Timely recognition of Lyme disease and treatment are imperative to facilitate recovery and prevent long-term sequelae.Footnote 2,Footnote 7,Footnote 8
The currently available Lyme disease test kits have been found to have limitations of sensitivity and specificity, particularly when used on patients with acute infection, which is usually easily treated with antibiotics.Footnote 7,Footnote 9 Even when the conventional two-tiered testing approach is used, the sensitivity and specificity of the combined test results can be less than optimal.Footnote 9,Footnote 10,Footnote 11 In a comprehensive study of 280 serum samples from well-characterized Lyme disease patients, the sensitivity of the two-tiered approach was as low as 38% for the sera of patients who had erythema migrans during the acute phase and 67% during their convalescence after antimicrobial treatment.Footnote 10 In late Lyme disease, the sensitivity increased to 87% for the sera of patients with early neuroborreliosis and to 97% for the sera of patients with Lyme arthritis.Footnote 10
Many factors contribute to false-negative or false-positive serologic test results for Lyme disease.Footnote 1,Footnote 7,Footnote 9,Footnote 11,Footnote 12,Footnote 13,Footnote 14 In general, false-negative results have been attributed to (a) a slow antibody response early in the course of the disease, (b) genetic diversity of B. burgdorferi and (c) treatment with antibiotics. False-positive results have been attributed to (a) cross-reacting antibodies due to other conditions or infections and (b) the persistence of antibodies after disease resolution. Variability in serologic test results for Lyme disease may also be related to interlaboratory differences and lack of interassay standardization.Footnote 9,Footnote 13,Footnote 14
In contrast to the known HIV serologic testing using the two-tiered algorithm to confirm diagnosis, the Lyme disease test kits are not designed to screen patients or to establish a clinical diagnosis.Footnote 9,Footnote 12 A positive test result does notnecessarily indicate current infection with B. burgdorferi, and a negative result, especially early in the course of infection, does not exclude B. burgdorferi infection as the cause of illness.Footnote 9,Footnote 10,Footnote 11,Footnote 12 Serologic test results should be used to support a clinical diagnosis of Lyme disease and should not be the primary basis for making diagnostic or treatment decisions.Footnote 1,Footnote 11 Diagnosis should be based on patient history, which includes symptoms and exposure to the tick vector, and physical findings.Footnote 4,Footnote 11,Footnote 15
Health care professionals should be aware of the limitations of Lyme disease test kits and are encouraged to report suspected incidents, including false-positive and false-negative results, to Health Canada.
Rana Filfil, PhD, Health Canada
Antiandrogens and hepatotoxicity
- A recent safety review conducted by Health Canada suggested that hepatotoxicity remains an important safety concern for all antiandrogen drugs.
- The frequency of these adverse reactions and their clinical features appear to differ from one drug to another.
- Health care professionals should be aware of the risk of hepatotoxicity associated with the use of these products.
Antiandrogens are a class of drugs used in androgen deprivation therapy for the treatment of advanced or metastatic prostate cancer. They are classified into two groups: nonsteroidal antiandrogens (flutamide, bicalutamide and nilutamide) and steroidal antiandrogens (cyproterone acetate).Footnote 111 Both groups work by competing with circulating androgens for receptor sites within the prostate cell, thus promoting apoptosis and inhibiting prostate cancer growth. Steroidal antiandrogens have the added ability of suppressing the production of testosterone. Depending on the drug, antiandrogens are indicated for use in monotherapy, or in combination with radiotherapy, luteinizing hormone-releasing hormone analogues or orchiectomy for complete androgen blockade.Footnote 121,Footnote 131,Footnote 141,Footnote 151
Antiandrogen drugs have been on the Canadian market for more than 20 years. Flutamide was approved by Health Canada in 1984 for the treatment of advanced stage B2 and stage C prostatic carcinoma and metastatic stage D2 prostate cancer.Footnote 121 Cyproterone acetate was approved in 1987 for the treatment of advanced prostatic carcinoma.Footnote 131 Bicalutamide and nilutamide were approved in 1996 and 1997 respectively for the treatment of metastatic stage D2 prostate cancer.Footnote 141,Footnote 151 Although the risk of hepatotoxicity and hepatic failure is currently labelled under the Warnings and Precautions sections of the Canadian product monographs for flutamide,Footnote 121 cyproterone acetate,Footnote 131 bicalutamideFootnote 141 and nilutamide,Footnote 151 a recent safety review conducted by Health Canada suggested that hepatotoxicity remains an important safety concern.
As of Mar. 31, 2012, Health Canada received 25 case reports of hepatotoxicity in men aged 60-98 years old that were suspected of being associated with antiandrogens, 24 of which were serious (Table 1). The most common adverse reactions included jaundice, increased liver enzyme levels, nausea, hepatic necrosis, ascites and hepatitis. One report of hepatotoxicity, excluded from Table 1, involved a woman using an antiandrogen for hirsutism.
The risk of hepatotoxicity with the use of antiandrogens has also been described in the clinical literature. Although both steroidal and nonsteroidal antiandrogens have been associated with hepatotoxicity, the frequency of these adverse reactions, and their clinical features, appear to differ from one drug to another.Footnote 111,Footnote 161,Footnote 171 For example, the results of an observational study showed a higher occurrence of hepatotoxicity among patients taking flutamide than among those taking cyproterone acetate (15.3% v. 9.5%, p = 0.034).Footnote 181 Furthermore, this study found that the occurrence of serious hepatotoxicity (defined as an elevation in liver enzyme levels greater than 6 times the upper limit of normal) was 4.8% with the use of flutamide and 3.8% with cyproterone acetate. Serious hepatotoxicity is reported to be rare with bicalutamide and nilutamide.Footnote 111
Data from published clinical studies and case reports from the Canada Vigilance database consistently suggest that the risk of hepatotoxicity has been associated with all antiandrogen products marketed in Canada. Health care professionals should be aware of the risk of hepatotoxicity associated with the use of these products.
Eduardo del Campo, MD, Health Canada
|Outcome of serious cases|
|Antiandrogen||Total no. of cases||No. of serious cases||Recovered||Not recovered||Death||Unknown|
Table 1 footnotes
Recent Canadian cases are selected based on their seriousness, frequency of occurrence or the fact that the reactions are unexpected. Case presentations are considered suspicions and are presented to stimulate reporting of similar suspected adverse reactions.
Thalomid and posterior reversible encephalopathy syndrome
Posterior reversible encephalopathy syndrome (PRES), also called reversible posterior leukoencephalopathy syndrome, is a neurological syndrome that typically includes the presence of headaches, visual disturbances, seizures, altered mental function and radiologic findings that commonly involve symmetrical posterior hemispheric edema.Footnote 11a It is often associated with abrupt hypertension and can also be seen in patients who are taking immunosuppressive drugs.Footnote 12a This syndrome is generally characterized by reversibility through control of the primary instigating factors.Footnote 11a
Thalidomide (Thalomid) is an immunomodulatory agent used to treat multiple myeloma.Footnote 13a It has been suggested that its immunosuppressive effect on endothelial cells may be involved in the development of PRES.Footnote 12a Some cases of PRES suspected of being associated with thalidomide have been reported in literature.Footnote 12a,Footnote 14a,Footnote 15a,Footnote 16a
One of the published cases had been reported to Health Canada. It involved a 49-year-old woman who had been taking thalidomide 200 mg/d for maintenance therapy after autologous stem cell transplantation for multiple myeloma. She had been taking thalidomide for about 11 months before experiencing two focal motor seizures that evolved into a witnessed generalized tonic-clonic seizure. The seizure was terminated with the administration of lorazepam, and she was normotensive upon physical examination. The patient had also experienced anxiety and subjective short-term memory loss. Magnetic resonance imaging (MRI) of the brain showed findings consistent with PRES, including multiple foci of hyperintensity in the occipital and posterior parietal lobes on T2-weighted images. The patient was prescribed phenytoin, which was later switched to valproic acid because of a possible drug allergy. Three months later, a follow-up MRI revealed complete resolution of the hyperintensity changes on T2-weighted images. The valproic acid therapy was tapered, and the patient did not have any further seizures. Health Canada encourages the reporting of similar suspected adverse reactions to the Canada Vigilance Program.
Quarterly Summary of health professional and consumer advisories
Table 1 footnotes
|Aug 10||Hospital beds||Update on the risk of patient entrapment|
|July 31||Calcitonin-containing drugs||Potential cancer risk with long-term use|
|July 25||Weight-loss health products||Unauthorized health products removed from sale at Burnaby's U-Box store|
|July 23||Pulmicort Turbuhaler
|Potential device failure|
|July 19||Vine Essence||Recall : unauthorized natural health
|July 16||Fu Fang Zaoren Jiaonang||Unauthorized health product removed from sale|
|July 11 & 13||ImmuCyst (BCG vaccine)||Update on facility issues and supply
|July 9 & 12||Volibris (ambrisentan)||Contraindication in patients with idiopathic pulmonary fibrosis|
|July 6||Lightning Rod||Unauthorized health product removed from sale|
|June 29||ZXT Gold Bee Pollen Capsules||Unauthorized health product removed from sale|
|June 28||Kleenex Luxury Foam Hand Sanitizer||Recall: microbial contamination|
|June 26||Paclitaxel for injection, 300mg/50mL||Glass vial defects for 3 lots|
|June 22||Counterfeit drugs||Reminder of the possible health risks|
|June 21||Natural Vigor Maximum||Recall: presence of undeclared dimethylhomosildenafil|
|June 15||Tuberculosis (BCG) vaccine||Recall: manufacturing facility problems|
|June 11 & 14||HepaGam B [Hepatitis B
Immune Globulin (Human) Injection]
|Possible risk of thrombotic events|
|June 1||Philips IntelliVue Patient
|Alarm problem with some units|
|May 29 & June 1||Privigen [Immune Globulin Intravenous (Human)]||Association with risk of hemolysis and labeling updates|
|May 28 & 31||Xgeva (denosumab)||Risk of severe symptomatic
hypocalcemia, including fatal case
|May 23||X-Rock, Kaboom and One
|Unauthorized health products removed from sale|
|May 15||Colleague Single and Triple Channel Volumetric Infusion Pumps||Important safety information|
|May 21 to Aug 19||Foreign products||17 Foreign Product Alerts (FPAs) were posted on the Health Canada Web site during this period; FPAs are available online or upon request|
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Canadian Adverse Reaction Newsletter
Marketed Health Products Directorate
Address Locator 0701D
Ottawa ON K1A 0K9
Patricia Carruthers-Czyzewski, BScPhm, MSc (Editor-in-Chief)
Hoa Ly, BSc
Emir Al-Khalili, BA, BScPhm
Benjamin Pearson, BSc
Aleksandar Brezar, BSc
Sophie Bourbonnais, BScPht
We thank the following members of the Expert Advisory Committee on the Vigilance of Health Products for their review of material for this issue: Colleen J. Metge, BSc(Pharm), PhD; and Yola Moride, PhD, FISPE.
Your comments are important to us. Let us know what you think.
Reporting Adverse Reactions
Canada Vigilance Program
© 2012 Her Majesty the Queen in Right of Canada. This publication may be reproduced without permission provided the source is fully acknowledged. The use of this publication for advertising purposes is prohibited. Health Canada does not assume liability for the accuracy or authenticity of the information submitted in case reports.
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