Adverse drug reactions: Part I

A qualitative exploration of pharmacovigilance policy implementation in Jordan, Oman, and Kuwait using Matland's ambiguity-conflict model

Background

As Arab countries seek to implement the ‘Guideline on Good Pharmacovigilance Practice (GVP) for Arab countries’, understanding policy implementation mechanisms and the factors impacting it can inform best implementation practice. This study aimed to explore the mechanisms of and factors influencing pharmacovigilance policy implementation in Arab countries with more established pharmacovigilance systems (Jordan, Oman), to inform policy implementation in a country with a nascent pharmacovigilance system (Kuwait).

Results

Matland’s ambiguity-conflict model served to frame data analysis from 56 face-to-face interviews, which showed that policy ambiguity and conflict were low in Jordan and Oman, suggesting an “administrative implementation” pathway. In Kuwait, policy ambiguity was high while sentiments about policy conflict were varied, suggesting a mixture between “experimental implementation” and “symbolic implementation”. Factors reducing policy ambiguity in Jordan and Oman included: decision-makers’ guidance to implementors, stakeholder involvement in the policy’s development and implementation, training of policy implementors throughout the implementation process, clearly outlined policy goals and means, and presence of a strategic implementation plan with appropriate timelines as well as a monitoring mechanism. In contrast, policy ambiguity in Kuwait stemmed from the absence or lack of attention to these factors. Factors reducing policy conflict included: the policy’s compliance with internationally recognised standards and the policy’s fit with local capabilities (all three countries), decision-makers’ cooperation with and support of the national centre as well as stakeholders’ agreement on policy goals and means (Jordan and Oman) and adopting a stepwise approach to implementation (Jordan).

Conclusions

Using Matland’s model, both the mechanism of and factors impacting successful pharmacovigilance policy implementation were identified. This informed recommendations for best implementation practice in Arab as well as other countries with nascent pharmacovigilance systems, including increased managerial engagement and support, greater stakeholder involvement in policy development and implementation, and undertaking more detailed implementation planning.

DNA damage by Withanone as a potential cause of liver toxicity observed for herbal products of Withania somnifera (Ashwagandha)

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The widely used medicinal herb Withania somnifera (Ashwagandha) has been recently reported to cause liver damage.

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Withanone is a major metabolite of Ashwagandha.

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Withanone was found to cause DNA damage.

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Withanone forms adducts with amines and thiols.

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Withanone-mediated DNA damage has serious biological consequences.

Withania somnifera, commonly known as Ashwagandha, is a medicinal plant used for thousands of years for various remedies. Extracts of Ashwagandha contain more than 200 metabolites, with withanone (win) being one of the major ones responsible for many of its medicinal properties. Recently, several cases of liver toxicity resulting from commercially available Ashwagandha products have been reported. The first report of Ashwagandha-related liver damage was from Japan, which was quickly resolved after drug-withdrawal. Later, similar cases of liver toxicity due to Ashwagandha consumption were reported from the USA and Iceland. Towards understanding the liver toxicity of Ashwagandha extracts, we studied win, a representative withanolide having toxicophores or structural alerts that are commonly associated with adverse drug reactions. We found that win can form non-labile adducts with the nucleosides dG, dA, and dC. Using various biochemical assays, we showed that win forms adducts in DNA and interfere with its biological property. Win also forms adducts with amines and this process is reversible. Based on the data presented here we concluded that win is detoxified by GSH but under limiting GSH levels it can cause DNA damage. The work presented here provides a potential mechanism for the reported Ashwagandha-mediated liver damage.

Impact of protocol change on individual factors related to course of adverse reactions to chemotherapy for breast cancer

PURPOSE

Asthenia, myalgia, arthralgia, mucositis, abdominal pain, diarrhea, and neutropenia are adverse reactions commonly reported by women undergoing chemotherapy. Traditional approaches do not take into account the effect that chemotherapeutic changes and variable interactions can cause in adverse reactions. We aimed to identify the impact of the change of a chemotherapy protocol within the same treatment in profiles associated with adverse reactions.

METHODS

A total of 166 women admitted to the Brazilian National Institute of Cancer (INCA) were followed. Polymorphisms, clinical variables, and FAC-D protocols (3 cycles of cyclophosphamide, 5-fluorouracil, and doxorubicin followed by 3 cycles of docetaxel) composed the set of independent variables analyzed. Reaction levels were recorded at the end of each chemotherapy cycle via interviews. Marginal models were fitted.

RESULTS

The results of marginal models for non-hematological reactions revealed that the docetaxel phase was associated with increased reaction levels compared with the FAC phase. In addition, the set of factors associated with the reactions changed in each protocol. The post-menopausal status was related to high levels of asthenia in docetaxel protocol whereas CYP2B6 polymorphism (rs3745274) was related to high levels in FAC protocol. Regarding the docetaxel phase, high levels of abdominal pain and mucositis were related to CBR3 gene (rs8133052) polymorphism and diabetes respectively.

CONCLUSION

The results suggest the need for monitoring non-hematological reactions during the docetaxel phase of FAC-D treatment. The factors related to more severe reactions depend on the chemotherapy protocol used.

Adverse Reactions to Medications: Concept Analysis and Development of a New Risk Nursing Diagnosis

PURPOSE

To analyze the concept of adverse reaction to medications and to develop the new nursing diagnosis Risk for Adverse Reactions to Medications.

METHODS

Concept analysis using Walker and Avant's eight step method.

FINDINGS

Thirty-three articles indexed in four databases were included. The components of the new nursing diagnosis were determined, including possible nursing outcomes and interventions.

CONCLUSIONS

The concept analysis supported the development of the new nursing diagnosis Risk for Adverse Reactions to Medications, which may help nurses to evaluate and identify patients susceptible to adverse reactions.

IMPLICATIONS FOR NURSING PRACTICE

The establishment of this nursing diagnosis will provide nurses an opportunity to implement interventions to anticipate and effectively intervene with patients at risk for this condition.

Reduction in exacerbation of COPD in patients of advanced age using the Japanese Kampo medicine Dai-kenchu-to: a retrospective cohort study

Purpose

Patients with symptomatic COPD are recommended to use inhaled bronchodilators containing long-acting muscarinic receptor antagonists (LAMAs). However, bronchodilators may cause gastrointestinal adverse effects due to anticholinergic reactions, especially in advanced-age patients with COPD. Dai-kenchu-to (TU-100, Da Jian Zhong Tang in Chinese) is the most frequently prescribed Japanese herbal Kampo medicine and is often prescribed to control abdominal bloating and constipation. The purpose of this study was to evaluate the role of Dai-kenchu-to as a supportive therapy in advanced-age patients with COPD.

Patients and methods

We used the Japanese Diagnosis Procedure Combination inpatient database and identified patients aged ≥75 years who were hospitalized for COPD exacerbation. We then compared the risk of re-hospitalization for COPD exacerbation or death between patients with and without Dai-kenchu-to using 1-to-4 propensity score matching. A Cox proportional hazards model was used to compare the two groups. We performed subgroup analyses for patients with and without LAMA therapy.

Results

Patients treated with Dai-kenchu-to had a significantly lower risk of re-hospitalization or death after discharge; the HR was 0.82 (95% CI, 0.67–0.99) in 1-to-4 propensity score matching. Subgroup analysis of LAMA users showed a significant difference in re-hospitalization or death, while subgroup analysis of LAMA non-users showed no significant difference.

Conclusion

Our findings indicate that Dai-kenchu-to may have improved the tolerability of LAMA in advanced-age patients with COPD and, therefore, reduced the risk of re-hospitalization or death from COPD exacerbation. Dai-kenchu-to may be recommended as a useful supportive therapy for advanced-age patients with COPD.

Renal xenobiotic transporter expression is altered in multiple experimental models of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is the most common chronic liver disease, which can progress to nonalcoholic steatohepatitis (NASH). Previous investigations demonstrated alterations in the expression and activity of hepatic drug transporters in NASH. Moreover, studies using rodent models of cholestasis suggest that compensatory changes in kidney transporter expression occur to facilitate renal excretion during states of hepatic stress; however, little information is currently known regarding extrahepatic regulation of drug transporters in NASH. The purpose of the current study was to investigate the possibility of renal drug transporter regulation in NASH across multiple experimental rodent models. Both rat and mouse NASH models were used in this investigation and include: the methionine and choline-deficient (MCD) diet, atherogenic diet, fa/fa rat, ob/ob and db/db mice. Histologic and pathologic evaluations confirmed that the MCD and atherogenic rats as well as the ob/ob and db/db mice all developed NASH. In contrast, the fa/fa rats did not develop NASH but did develop extensive renal injury compared with the other models. Renal mRNA and protein analyses of xenobiotic transporters suggest that compensatory changes occur in NASH to favor increased xenobiotic secretion. Specifically, both apical efflux and basolateral uptake transporters are induced, whereas apical uptake transporter expression is repressed. These results suggest that NASH may alter the expression and potentially function of renal drug transporters, thereby impacting drug elimination mechanisms in the kidney.

Drug disposition alterations in liver disease: extrahepatic effects in cholestasis and nonalcoholic steatohepatitis

INTRODUCTION

The pharmacokinetics (PK) of drugs and xenobiotics, namely pharmaceuticals, is influenced by a host of factors that include genetics, physiological factors and environmental stressors. The importance of disease on the disposition of xenobiotics has been increasingly recognized among medical professionals for alterations in key enzymes and membrane transporters that influence drug disposition and contribute to the development of adverse drug reactions.

AREAS COVERED

This review will survey pertinent literature of how liver disease alters the PKs of drugs and other xenobiotics. The focus will be on nonalcoholic steatohepatitis as well as cholestatic liver diseases. A review of basic pharmacokinetic principles, with a special emphasis on xenobiotic metabolizing enzymes and membrane transporters, will be provided. Specifically, examples of how genetic alterations affect metabolism and excretion, respectively, will be highlighted. Lastly, the idea of 'extrahepatic' regulation will be explored, citing examples of how disease manifestation in the liver may affect drug disposition in distal sites, such as the kidney.

EXPERT OPINION

An expert opinion will be provided highlighting the definite need for data in understanding extrahepatic regulation of membrane transporters in the presence of liver disease and its potential to dramatically alter the PK and toxicokinetic profile of numerous drugs and xenobiotics.

Modeling human nonalcoholic steatohepatitis-associated changes in drug transporter expression using experimental rodent models

Nonalcoholic fatty liver disease is a prevalent form of chronic liver disease that can progress to the more advanced stage of nonalcoholic steatohepatitis (NASH). NASH has been shown to alter drug transporter regulation and may have implications in the development of adverse drug reactions. Several experimental rodent models have been proposed for the study of NASH, but no single model fully recapitulates all aspects of the human disease. The purpose of the current study was to determine which experimental NASH model best reflects the known alterations in human drug transporter expression to enable more accurate drug disposition predictions in NASH. Both rat and mouse NASH models were used in this investigation and include the methionine and choline deficient (MCD) diet model, atherogenic diet model, ob/ob and db/db mice, and fa/fa rats. Pathologic scoring evaluations demonstrated that MCD and atherogenic rats, as well as ob/ob and db/db mice, developed NASH. Liver mRNA and protein expression analyses of drug transporters showed that in general, efflux transporters were induced and uptake transporters were repressed in the rat MCD and the mouse ob/ob and db/db models. Lastly, concordance analyses suggest that both the mouse and rat MCD models as well as mouse ob/ob and db/db NASH models show the most similarity to human transporter mRNA and protein expression. These results suggest that the MCD rat and mouse model, as well as the ob/ob and db/db mouse models, may be useful for predicting altered disposition of drugs with similar kinetics across humans and rodents.

Adverse events attributable to nocebo in randomized controlled drug trials in fibromyalgia syndrome and painful diabetic peripheral neuropathy: systematic review

OBJECTIVE

The objectives of the study were to determine the impact of nocebo effects on adverse events (AEs) in drug trials in fibromyalgia syndrome (FMS) and painful diabetic peripheral neuropathy (DPN).

METHODS

MEDLINE, CENTRAL, SCOPUS, and the databases of the U.S. National Institutes of Health and the Pharmaceutical Research and Manufacturers of America were searched until December 31, 2010. Randomized controlled trials with a parallel design of any drug therapy compared with pharmacological placebo in patients with FMS and DPN were included. Pooled estimates of nocebo effects (number of patients with at least 1 AE and dropping out due AEs) were calculated for placebo and true drug groups by a random effects model.

RESULTS

Fifty-eight FMS (62 DPN) trials included a total of 5065 (5095) patients in placebo groups. The quality of reporting the assessment strategy of AEs was poor in most trials. The pooled estimate of the event rate drop out rate due to AEs in placebo groups was 9.6 [95% confidence control (CI): 8.6-10.7] in placebo and 16.3 (95% CI: 14.1-31.2) in true drug groups of FMS trials and was 5.8 (95% CI: 5.1-6.6) in placebo and 13.2 (95% CI: 10.7-16.2) in true drug groups of DPN trials. Nocebo effects accounted for 72.0% (44.9) of the drop outs in true drug groups in FMS (DPN).

DISCUSSION

Nocebo effects substantially accounted for AEs in drug trials of FMS and DPN. Standards to assess and report AEs should be defined by regulatory agencies. Strategies to minimize nocebo effects in both clinical trials and clinical practice should be developed.

A systematic review of validated methods for identifying hypersensitivity reactions other than anaphylaxis (fever, rash, and lymphadenopathy), using administrative and claims data

PURPOSE

The Food and Drug Administration's Mini-Sentinel pilot program aims to conduct active surveillance to refine safety signals that emerge for marketed medical products. A key facet of this surveillance is to develop and understand the validity of algorithms for identifying health outcomes of interest from administrative and claims data. This article summarizes the process and findings of the algorithm review of hypersensitivity reactions.

METHODS

PubMed and Iowa Drug Information Service searches were conducted to identify citations applicable to the hypersensitivity reactions of health outcomes of interest. Level 1 abstract reviews and Level 2 full-text reviews were conducted to find articles using administrative and claims data to identify hypersensitivity reactions and including validation estimates of the coding algorithms.

RESULTS

We identified five studies that provided validated hypersensitivity-reaction algorithms. Algorithm positive predictive values (PPVs) for various definitions of hypersensitivity reactions ranged from 3% to 95%. PPVs were high (i.e. 90%-95%) when both exposures and diagnoses were very specific. PPV generally decreased when the definition of hypersensitivity was expanded, except in one study that used data mining methodology for algorithm development.

CONCLUSIONS

The ability of coding algorithms to identify hypersensitivity reactions varied, with decreasing performance occurring with expanded outcome definitions. This examination of hypersensitivity-reaction coding algorithms provides an example of surveillance bias resulting from outcome definitions that include mild cases. Data mining may provide tools for algorithm development for hypersensitivity and other health outcomes. Research needs to be conducted on designing validation studies to test hypersensitivity-reaction algorithms and estimating their predictive power, sensitivity, and specificity.

Variations in ATP-binding cassette transporter regulation during the progression of human nonalcoholic fatty liver disease

Transporters located on the sinusoidal and canalicular membranes of hepatocytes regulate the efflux of drugs and metabolites into blood and bile, respectively. Changes in the expression or function of these transporters during liver disease may lead to a greater risk of adverse drug reactions. Nonalcoholic fatty liver disease (NAFLD) is a progressive condition encompassing the relatively benign steatosis and the more severe, inflammatory state of nonalcoholic steatohepatitis (NASH). Here, we present an analysis of the effect of NAFLD progression on the major ATP-binding cassette (ABC) efflux transport proteins ABCC1-6, ABCB1, and ABCG2. Human liver samples diagnosed as normal, steatotic, NASH (fatty), and NASH (not fatty) were analyzed. Increasing trends in mRNA expression of ABCC1, ABCC4-5, ABCB1, and ABCG2 were found with NAFLD progression, whereas protein levels of all transporters exhibited increasing trends with disease progression. Immunohistochemical staining of ABCC3, ABCB1, and ABCG2 revealed no alterations in cellular localization during NAFLD progression. ABCC2 staining revealed an alternative mechanism of regulation in NASH in which the transporter appears to be internalized away from the canalicular membrane. This correlated with a preferential shift in the molecular mass of ABCC2 from 200 to 180 kDa in NASH, which has been shown to be associated with a loss of glycosylation and internalization of the protein. These data demonstrate increased expression of multiple efflux transporters as well as altered cellular localization of ABCC2 in NASH, which may have profound effects on the ability of patients with NASH to eliminate drugs in an appropriate manner.