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

Use of pharmacological and nonpharmacological treatments for chronic noncancer pain among people using opioids: a longitudinal cohort study

ABSTRACT

Although multimodal management of chronic noncancer pain (CNCP) is recommended, long-term treatment utilization patterns among people using opioids are not well known. The Pain and Opioids IN Treatment study recruited Australian adults receiving opioids for CNCP for more than 6 weeks from community pharmacies. Pharmacological (opioid and nonopioid analgesics and psychotropic medicines) and nonpharmacological (physical, mental health, and specialized) treatments used in the previous 12 months and 30 days were collected annually over 4 years (2015-2018). Associations were explored between 30-day treatment use and sociodemographic characteristics and pain measures. Overall, 1334 participants completed at least one annual follow-up. The median pain severity (5.0, interquartile range [IQR] 3.8 to 6.3) and pain interference scores (5.7, IQR 3.9-7.3) indicated moderate pain throughout the study period, despite most participants reporting the use of nonopioid pharmacological (12 month: 97.6% and 30 day: 96.8%) and nonpharmacological treatments (12 month: 91.8% and 30 day: 66.1%). Some treatment use was inconsistent with guidelines: ongoing nonsteroidal anti-inflammatory drugs and sedative-hypnotic use were common, whereas fewer people engaged with pain management programs (12 month: 22.3%). Private health insurance was associated with using physical (adjusted odds ratio 1.61, 99.5% confidence intervals 1.15-2.24) and specialized nonpharmacological treatments (adjusted odds ratio 1.47, 99.5% confidence intervals 1.14-1.91). This study demonstrates that many Australians taking opioids long-term for CNCP also use nonopioid pharmacological and nonpharmacological treatments. The use of pharmacological treatments including nonsteroidal anti-inflammatory drugs, psychotropic medicines, and gabapentinoids, outside guidelines, warrants review. Furthermore, despite Australia's universal healthcare scheme subsidising some nonpharmacological treatments, overall use of these treatments was associated with having private health insurance, highlighting a need for more equitable service provision.

High-Dose Acetaminophen Alters the Integrity of the Blood-Brain Barrier and Leads to Increased CNS Uptake of Codeine in Rats

The consumption of acetaminophen (APAP) can induce neurological changes in human subjects; however, effects of APAP on blood-brain barrier (BBB) integrity are unknown. BBB changes by APAP can have profound consequences for brain delivery of co-administered drugs. To study APAP effects, female Sprague-Dawley rats (12-16 weeks old) were administered vehicle (i.e., 100% dimethyl sulfoxide (DMSO), intraperitoneally (i.p.)) or APAP (80 mg/kg or 500 mg/kg in DMSO, i.p.; equivalent to a 900 mg or 5600 mg daily dose for a 70 kg human subject). BBB permeability was measured via in situ brain perfusion using [¹⁴C]sucrose and [³H]codeine, an opioid analgesic drug that is co-administered with APAP (i.e., Tylenol #3). Localization and protein expression of tight junction proteins (i.e., claudin-5, occludin, ZO-1) were studied in rat brain microvessels using Western blot analysis and confocal microscopy, respectively. Paracellular [¹⁴C]sucrose "leak" and brain [³H]codeine accumulation were significantly enhanced in rats treated with 500 mg/kg APAP only. Additionally, claudin-5 localization and protein expression were altered in brain microvessels isolated from rats administered 500 mg/kg APAP. Our novel and translational data show that BBB integrity is altered following a single high APAP dose, results that are relevant to patients abusing or misusing APAP and/or APAP/opioid combination products.

Modulation of Opioid Transport at the Blood-Brain Barrier by Altered ATP-Binding Cassette (ABC) Transporter Expression and Activity

Opioids are highly effective analgesics that have a serious potential for adverse drug reactions and for development of addiction and tolerance. Since the use of opioids has escalated in recent years, it is increasingly important to understand biological mechanisms that can increase the probability of opioid-associated adverse events occurring in patient populations. This is emphasized by the current opioid epidemic in the United States where opioid analgesics are frequently abused and misused. It has been established that the effectiveness of opioids is maximized when these drugs readily access opioid receptors in the central nervous system (CNS). Indeed, opioid delivery to the brain is significantly influenced by the blood-brain barrier (BBB). In particular, ATP-binding cassette (ABC) transporters that are endogenously expressed at the BBB are critical determinants of CNS opioid penetration. In this review, we will discuss current knowledge on the transport of opioid analgesic drugs by ABC transporters at the BBB. We will also examine how expression and trafficking of ABC transporters can be modified by pain and/or opioid pharmacotherapy, a novel mechanism that can promote opioid-associated adverse drug events and development of addiction and tolerance.

Prevalence of exceeding maximum daily dose of paracetamol, and seasonal variations in cold-flu season

AIMS

To estimate prevalence of excess intake of paracetamol and investigate seasonal variations therein.

METHODS

Between 2011 and 2016, 14 481 US adults who used paracetamol in the preceding 30 days were sampled from national online panels and completed a detailed online daily diary of paracetamol medication use for 7 days. Respondents were not told that the study concerned paracetamol. Cold/flu season (CFS), identified using Google Trends data, was contrasted to off-season in symptoms, use of paracetamol medications, and consumption exceeding 4 g (the recommended daily maximum).

RESULTS

Overall, 6.3% [95% confidence interval: 5.9-6.7%] of users exceeded 4 g on at least one day; 3.7% [3.5-3.8%] of usage days exceeded 4 g. Cold/flu symptoms were more likely to be experienced and treated with paracetamol in CFS than off-season. Paracetamol users were more likely to exceed 4 g during CFS (6.5% vs. 5.3%; odds ratio = 1.24, 1.04-1.48); days exceeding 4 g also increased (3.9% vs. 2.8%; odds ratio = 1.37, 1.11-1.69). This was not due to differences in characteristics of individuals using paracetamol in CFS, but primarily to increased use of over-the-counter combination medications designed to treat upper respiratory cold/flu symptoms (33.2% of usage days in CFS vs. 24.8% in off-season; odds ratio = 1.58, 1.46-1.72). When such medications were omitted, there was no statistically significant seasonal variation in exceeding 4 g.

CONCLUSIONS

Paracetamol use and over-dosing increases in CFS, primarily due to increased use of over-the-counter combinations treating upper respiratory cold/flu symptoms. Pharmacists should warn users to follow labelled dosing directions, especially during CFS.

Opioid Prescribing Patterns and Costs in a Large Group of Patients in Colombia

The potential for development of tolerance and dependence and the risk of side effects of opioids make it necessary to monitor their prescribing patterns in order to decrease the morbidity and mortality associated with their continued use. The objective of this study was to determine prescription patterns of opioid medication in a group of patients through a cross-sectional study on a population database of 3.5 million people. Patients with three months of continuous opioid use were identified. Pharmacological, co-medication and cost variables were analyzed. We conducted a multivariate analysis. A total of 7,457 patients were included; 72.1% were women, the mean age was 65.1 years, and 3.8% had a diagnosis of cancer. 10.2% of the patients received opioids in combination therapy. The most prescribed opioids were codeine (57.7%), tramadol (30.9%), and hydrocodone (10.4%). The great majority of patients (91.8%) received pharmacological co-medication with antihypertensive agents (54.4%), statins (38.2%) and acetaminophen (35.4%). The use of other analgesics such as acetaminophen (OR: 1.45, 95% CI: 1.22 -1.75) or nonsteroidal anti-inflammatory drugs (OR: 1.98, 95% CI: 1.60 -2.44) was associated with increased risk of receiving opioids in combination therapy. Prescribing habits of weak agonists and short-acting opioids predominate, mainly in monotherapy and at lower than recommended doses.