Risk of Hepatotoxicity-Related Hospitalizations among Patients Treated with Opioid/Acetaminophen Combination Prescription Pain Medications

Risk of hospital admission for liver injury in users of NSAIDs and nonoverdose paracetamol: Preliminary results from the EPIHAM study

PURPOSE

The SALT study found similar per-user risks of acute liver failure (ALF) leading to transplantation (ALFT) between NSAIDs and a threefold higher risk in nonoverdose paracetamol (NOP) users. The objective of EPIHAM was to identify the risks of hospital admission for acute liver injury (ALI) associated with NSAIDs and NOP.

METHODS

Case-population study in the 1/97 sample of the French population claims database. Acute liver injury was identified from hospital discharge summaries, from 2009 to 2013. Exposure for cases was dispensing of NSAID or NOP resulting in exposure within 30 days before admission. Population exposure was the number of patients using the drugs over the study timeframe and total number of DDD dispensed.

RESULTS

Of 63 cases of ALI, 13 had been exposed to NSAIDs and 24 to NOP. Events per million DDD (95% CI) ranged from 0.46 (0.09-1.34) (ketoprofen) to 1.43 (0.04-7.97) (diclofenac combinations), 0.43 (0.23-0.73) all NSAIDs combined, 0.58 (0.37-0.86) for NOP. There was no association with average duration of treatment. Per patient risk ranged from 19.5 (5.31-49.9) (ibuprofen) per million users to 37.2 (19.8-63.6) all NSAIDs combined, 58.0 (37.2-86.3) for NOP. There was a linear relationship between average treatment duration and per-user risk (R²  = 0.51, P < .05 for NSAIDs, R²  = 0.97, P < .01 for NOP).

CONCLUSIONS

Risk of hospital admission for ALI with NSAIDs and NOP was similar and indicative of a dose and duration-related effect (pharmacological) effect. Acute liver injury rates were not predictive of ALFT risk.

Unintentional mortality associated with paracetamol and codeine preparations, with and without doxylamine, in Australia

INTRODUCTION

Misuse of paracetamol, codeine and doxylamine combination analgesics may lead to addiction and mortality. This study aimed to (1) identify unintentional deaths in Australia associated with use of combination analgesic products containing paracetamol, codeine and doxylamine; (2) describe cases characteristics, including demographics and additional medication use; and (3) identify common factors associated with misuse and mortality of these medicines in Australia.

DESIGN

This retrospective case series analysed National Coronial Information System data to identify cases of unintentional death attributable to paracetamol, codeine and doxylamine products between 2002 and 2012.

SETTING

Three Eastern Australian states: New South Wales, Queensland, Victoria, comprising a population of approximately 18.6 million people.

RESULTS

441 unintentional deaths attributed to paracetamol/codeine products were identified; doxylamine was detected in 102 cases (23%). Overall unintentional death rates rose from 0.9-per-million in 2002 to 3.6-per-million in 2009, declining to 1.9-per-million in 2012. Median age at time of death was 48, half of all cases occurred between 35-54 years of age, and 57% were female. Concomitant medication use was detected in 79% of cases, including benzodiazepines, other opioids, psychiatric medications, alcohol and illicit drugs. Behaviours consistent with drug misuse including doctor/pharmacy shopping, excessive dosages and extended use, were identified in 24% of cases.

CONCLUSIONS

This study identified 441 deaths associated with codeine-combination analgesic products across three Australian states; with an average of 40 deaths per year. Death commonly involved multiple substance use and abuse behaviours indicative of misuse and dependence.

The use of paracetamol (acetaminophen) among a community sample of people with chronic non-cancer pain prescribed opioids

BACKGROUND

The regular use of simple analgesics in addition to opioids such as paracetamol (or acetaminophen) is recommended for persistent pain to enhance analgesia. Few studies have examined the frequency and doses of paracetamol among people with chronic non-cancer pain including use above the recommended maximum daily dose.

AIMS

To assess (i) the prevalence of paracetamol use among people with chronic non-cancer pain prescribed opioids, (ii) assess the prevalence of paracetamol use above the recommended maximum daily dose and (iii) assess correlates of people who used paracetamol above the recommended maximum daily dose including: age, gender, income, education, pain severity and interference, use of paracetamol/opioid combination analgesics, total opioid dose, depression, anxiety, pain self-efficacy or comorbid substance use, among people prescribed opioids for chronic non-cancer pain.

METHODS

This study draws on baseline data collected for the Pain and Opioids IN Treatment (POINT) study and utilises data from 962 interviews and medication diaries. The POINT study is national prospective cohort of people with chronic non-cancer pain prescribed opioids. Participants were recruited from randomly selected pharmacies across Australia.

RESULTS

Sixty-three per cent of the participants had used paracetamol in the past week (95% CI = 59.7-65.8). Among the paracetamol users 22% (95% CI = 19.3-24.6) had used paracetamol/opioid combination analgesics and 4.8% (95% CI = 3.6-6.3) had used paracetamol above the recommended maximum daily dose (i.e. > 4000 mg/day). Following binomial logistic regression (χ(2) = 25.98, df = 10, p = 0.004), people who had taken above the recommended maximum daily dose were less likely to have low income (AOR = 0.52, 95% CI = 0.27-0.99), more likely to use paracetamol/opioid combination analgesics (AOR = 2.01, 95% CI = 1.02-3.98) and more likely to take a higher opioid dose (AOR = 1.00, 95% CI = 1.00-1.01).

CONCLUSION

The majority of people with chronic non-cancer pain prescribed opioids report using paracetamol appropriately. High income, use of paracetamol/opioid combination analgesics and higher opioid dose were independently associated with paracetamol use above the recommended maximum daily dose.

Drugs of abuse and addiction: A slippery slope toward liver injury

Substances of abuse induce alteration in neurobehavioral symptoms, which can lead to simultaneous exacerbation of liver injury. The biochemical changes of liver are significantly observed in the abused group of people using illicit drugs or drugs that are abused. A huge amount of work has been carried out by scientists for validation experiments using animal models to assess hepatotoxicity in cases of drugs of abuse. The risk of hepatotoxicity from these psychostimulants has been determined by different research groups. Hepatotoxicity of these drugs has been recently highlighted and isolated case reports always have been documented in relation to misuse of the drugs. These drugs induce liver toxicity on acute or chronic dose dependent process, which ultimately lead to liver damage, acute fatty infiltration, cholestatic jaundice, liver granulomas, hepatitis, liver cirrhosis etc. Considering the importance of drug-induced hepatotoxicity as a major cause of liver damage, this review emphasizes on various drugs of abuse and addiction which induce hepatotoxicity along with their mechanism of liver damage in clinical aspect as well as in vitro and in vivo approach. However, the mechanisms of drug-induced hepatotoxicity is dependent on reactive metabolite formation via metabolism, modification of covalent bonding between cellular components with drug and its metabolites, reactive oxygen species generation inside and outside of hepatocytes, activation of signal transduction pathways that alter cell death or survival mechanism, and cellular mitochondrial damage, which leads to alteration in ATP generation have been notified here. Moreover, how the cytokines are modulated by these drugs has been mentioned here.

A multicenter, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of single-entity, once-daily hydrocodone tablets in patients with uncontrolled moderate to severe chronic low back pain

OBJECTIVES

This multicenter, randomized, double-blind, placebo-controlled study with an enriched enrollment, randomized withdrawal design was conducted to evaluate the analgesic efficacy and safety of single-entity, once-daily hydrocodone 20 to 120 mg tablets (HYD) in opioid-naive and opioid-experienced patients with uncontrolled moderate to severe chronic low back pain (CLBP).

RESEARCH DESIGN AND METHODS

The primary endpoint was week 12 pain intensity scores (11-point scale, 0 = no pain) using a mixed effect model with repeated measures incorporating a pattern mixture model framework. Responder analysis was a secondary endpoint. Safety was assessed.

RESULTS

Out of 905 patients who were treated with HYD during the open-label titration period, 588 (65%) were randomized to continue to receive HYD (n = 296, 20 - 120 mg taken once daily, average daily dose 57 mg) or a matching placebo (n = 292). HYD demonstrated superior pain reduction (p = 0.0016); this result was supported by sensitivity analyses using different approaches to handling missing data. Proportions of patients achieving ≥ 30 and ≥ 50% improvement in pain from screening to week 12 also favored HYD (p = 0.0033 and 0.0225, respectively). HYD was generally well tolerated.

CONCLUSIONS

HYD was shown to be an efficacious treatment for CLBP in this study. There were no new or unexpected safety concerns detected.

The Potential Role of an Extended-Release, Abuse-Deterrent Oxycodone/Acetaminophen Fixed-Dose Combination Product for the Treatment of Acute Pain

Acute pain, prevalent as part of postoperative and traumatic pain, is often sub-optimally or inadequately treated. Fixed-dose combination analgesic products that combine a reduced amount of opioid with a nonopioid analgesic such as acetaminophen (paracetamol) in a single tablet offer potential pharmacodynamic and/or pharmacokinetic benefits, and may also result in an opioid-sparing effect. A new analgesic product (XARTEMIS™ XR, Mallinckrodt Brand Pharmaceuticals, Dublin, Ireland) combines oxycodone (7.5 mg) with acetaminophen (325 mg) in an immediate-release/extended-release (ER) formulation that is indicated for the treatment of acute pain. The ER formulation of this product provides stable serum drug concentrations that in this case lasts 12 h. Oxycodone/acetaminophen is a drug combination that offers safe and effective pain relief in a variety of acute pain syndromes such as postoperative pain. The combination formulation allows a smaller amount of oxycodone per tablet and the biphasic-layered matrix of the pill for ER may present obstacles to potential abusers. No opioid is totally abuse resistant, but the lower opioid content and tamper-resistant formulation of this product might discourage abuse. Clinicians must still be mindful of the acetaminophen part of this product in the patient’s overall daily intake (in light of acetaminophen hepatotoxicity). The new product appears to provide an important new choice in the armamentarium against acute pain.

Assessment of case definitions for identifying acute liver injury in large observational databases

BACKGROUND

Determining the aetiology of acute liver injury (ALI) may be challenging to both clinicians and researchers. Observational research is particularly useful in studying rare medical outcomes such as ALI; however, case definitions for ALI in previous observational studies lack consistency and sensitivity. ALI is a clinically important condition with various aetiologies, including drug exposure.

OBJECTIVE

The aim of this study was to evaluate four distinct case definitions for ALI across a diverse set of large observational databases, providing a better understanding of ALI prevalence and natural history.

DATA SOURCES

Seven healthcare databases: GE Healthcare, MarketScan(®) Lab Database, Humana Inc., Partners HealthCare System, Regenstrief Institute, SDI Health (now IMS Health, Inc.), and the National Patient Care Database of the Veterans Health Administration.

METHODS

We evaluated prevalence of ALI through the application of four distinct case definitions across seven observational healthcare databases. We described how laboratory and clinical characteristics of identified case populations varied across definitions and examined the prevalence of other hepatobiliary disorders among identified ALI cases that may decrease suspicion of drug-induced liver injury (DILI) in particular.

RESULTS

This study demonstrated that increasing the restrictiveness of the case definition resulted in fewer cases, but greater prevalence of ALI clinical features. Considerable heterogeneity in the frequency of laboratory testing and results observed among cases meeting the most restrictive definition suggests that the clinical features, monitoring patterns and suspicion of ALI are highly variable among patients.

CONCLUSIONS

Creation of four distinct case definitions and application across a disparate set of observational databases resulted in significant variation in the prevalence of ALI. A greater understanding of the natural history of ALI through examination of electronic healthcare data can facilitate development of reliable and valid ALI case definitions that may enhance the ability to accurately identify associations between ALI and drug exposures. Considerable heterogeneity in laboratory values and frequency of laboratory testing among individuals meeting the criteria for ALI suggests that the evaluation of ALI is highly variable.

A perspective on the epidemiology of acetaminophen exposure and toxicity in the United States

Acetaminophen is a commonly-used analgesic in the US and, at doses of more than 4 g/day, can lead to serious hepatotoxicity. Recent FDA and CMS decisions serve to limit and monitor exposure to high-dose acetaminophen. This literature review aims to describe the exposure to and consequences of high-dose acetaminophen among chronic pain patients in the US. Each year in the US, approximately 6% of adults are prescribed acetaminophen doses of more than 4 g/day and 30,000 patients are hospitalized for acetaminophen toxicity. Up to half of acetaminophen overdoses are unintentional, largely related to opioid-acetaminophen combinations and attempts to achieve better symptom relief. Liver injury occurs in 17% of adults with unintentional acetaminophen overdose.

Hepatotoxicity and drug interactions in liver transplant candidates and recipients

In this article the medications that have been shown to increase rates of drug-induced liver injury in patients with cirrhosis and the important drug-drug interactions in recipients of liver transplantation are reviewed. In general, the risk of drug-induced liver injury in patients with cirrhosis does not seem to be higher when compared with the noncirrhotic population. There are, however, 2 classes of agents that have been implicated-medications used to treat tuberculosis and medications used to treat human immunodeficiency virus infection. However, with careful monitoring, even significant interactions can be effectively managed.

Expert panel assessment of acute liver injury identification in observational data

BACKGROUND

Observational data are useful for studying drug safety; however, to be effective, accurate outcome measurement is paramount.

OBJECTIVES

This study compared alternative outcome definitions for acute liver injury (ALI) and explored opportunities for improving ALI identification in observational data.

METHODS

The Truven MarketScan® Lab Database (MSLR) was used to identify patients meeting at least 1 of 4 ALI definitions, including definitions based on diagnosis codes, laboratory measures, or combinations of diagnoses, procedures, and/or laboratory measures. Expert panelists reviewed patient data using a Web dashboard. Panelists determined whether they believed the patient had ALI and identified factors influencing their decision. Logistic regression models explored which factors were influential in case determination.

RESULTS

Overall, only 37 of 208 reviewed patients (17.8%) were classified as cases. The diagnosis-based definition yielded no positive cases and the laboratory-based definition yielded the most positive cases (31 of 60). The most influential factors in case classification were occurrence of procedures after the index date (OR = 13.2, 95% CI = 5.3-32.9), no occurrence of drug treatments before the index date (OR = 4.6; 95% CI = 1.6-13.2), occurrence of drug treatments before the index date (OR = 0.3; 95% CI = 0.1-0.6), and no drug treatments after the index date (OR = 0.2; 95% CI = 0.0-0.5).

CONCLUSIONS

Comparing ALI definitions illustrated tradeoffs between the number of plausible cases identified and the likelihood of cases being classified as positive. Future research should refine ALI case definitions, considering the import of laboratory results, procedures, and drugs in defining a case.

A survey of adult awareness and use of medicine containing acetaminophen

PURPOSE

To compare awareness, use of acetaminophen, and preferences for receiving information aimed at reducing acetaminophen overdose.

METHODS

A survey of health plan enrollees identified from automated pharmacy data who were long-term and acute users of opioids with acetaminophen (n = 720 each cohort), and a general population cohort (n = 360) during the 2010-2011 cold/flu season. A 74% response rate was achieved. Differences were tested across the three cohorts, and by level of education, using age-adjusted regression models.

RESULTS

Use of over-the-counter or prescription medicine containing acetaminophen in the prior 2 weeks was reported by 84% in the long-term opioid cohort, 76% in the acute opioid cohort, and 36% in the general population, but use of over-the-counter medicine with acetaminophen did not differ across the cohorts (30-34%). All three cohorts were unlikely to correctly identify drugs containing acetaminophen, but the opioid cohorts performed slightly better than the general population. Those with higher education performed slightly better when asked to identify acetaminophen products than those with no college education. The average usual daily acetaminophen dose (mg/day) reported was highest in the long-term opioid cohort (1185), followed by the acute opioid cohort (1010), and the general population (891)-p < 0.001. Estimated supratherapeutic exposure (>4000 mg/day) was rare but three to five times more common in the opioid cohorts than in the general population.

CONCLUSIONS

Acetaminophen use is common, and supratherapeutic exposure may be of concern in users of opioids. Knowledge of which drugs contain acetaminophen appears inadequate; better labeling and proactive education from professionals may be impactful.

Removal of opioid/acetaminophen combination prescription pain medications: assessing the evidence for hepatotoxicity and consequences of removal of these medications

Opioid/acetaminophen combination products are widely prescribed for the management of moderate to moderately severe pain. Acetaminophen, when improperly used, can lead to liver damage and even acute liver failure. In June 2009, an FDA advisory committee recommended elimination of prescription acetaminophen combination products because of the risk of hepatotoxicity associated with use of these medications. The FDA advisory committee reviewed numerous observational studies and adverse event reporting data. The aims of this article are to: 1) provide a summary and epidemiologic critique of the studies and evidence the FDA advisory committee reviewed; 2) examine the potential consequences, such as poorly managed pain or a shift to treatment with other medications with greater potential toxicity and/or restricted availability, if the FDA follows the advisory committee vote; and 3) outline alternate strategies the FDA should consider for reducing hepatotoxicity associated with opioid/acetaminophen combination products.