Six-year follow-up of impact of co-proxamol withdrawal in England and Wales on prescribing and deaths: time-series study.

BACKGROUND: The analgesic co-proxamol (paracetamol/dextropropoxyphene combination) has been widely involved in fatal poisoning. Concerns about its safety/effectiveness profile and widespread use for suicidal poisoning prompted its withdrawal in the UK in 2005, with partial withdrawal between 2005 and 2007, and full withdrawal in 2008. Our objective in this study was to assess the association between co-proxamol withdrawal and prescribing and deaths in England and Wales in 2005-2010 compared with 1998-2004, including estimation of possible substitution effects by other analgesics. METHODS AND FINDINGS: We obtained prescribing data from the NHS Health and Social Care Information Centre (England) and Prescribing Services Partneriaeth Cydwasanaethau GIG Cymru (Wales), and mortality data from the Office for National Statistics. We carried out an interrupted time-series analysis of prescribing and deaths (suicide, open verdicts, accidental poisonings) involving single analgesics. The reduction in prescribing of co-proxamol following its withdrawal in 2005 was accompanied by increases in prescribing of several other analgesics (co-codamol, paracetamol, codeine, co-dydramol, tramadol, oxycodone, and morphine) during 2005-2010 compared with 1998-2004. These changes were associated with major reductions in deaths due to poisoning with co-proxamol receiving verdicts of suicide and undetermined cause of -21 deaths (95% CI -34 to -8) per quarter, equating to approximately 500 fewer suicide deaths (-61%) over the 6 years 2005-2010, and -25 deaths (95% CI -38 to -12) per quarter, equating to 600 fewer deaths (-62%) when accidental poisoning deaths were included. There was little observed change in deaths involving other analgesics, apart from an increase in oxycodone poisonings, but numbers were small. Limitations were that the study was based on deaths involving single drugs alone and changes in deaths involving prescribed morphine could not be assessed. CONCLUSIONS: During the 6 years following the withdrawal of co-proxamol in the UK, there was a major reduction in poisoning deaths involving this drug, without apparent significant increase in deaths involving other analgesics.

Use of analgesics in intentional drug overdose presentations to hospital before and after the withdrawal of distalgesic from the Irish market.

BACKGROUND: Distalgesic, the prescription-only analgesic compound of paracetamol (325 mg) and dextropropoxyphene (32.5 mg) known as co-proxamol in the UK, was withdrawn from the Irish market as of January 2006. This study aimed to evaluate the impact of the withdrawal of distalgesic in terms of intentional drug overdose (IDO) presentations to hospital emergency departments (EDs) nationally. METHODS: A total of 42,849 IDO presentations to 37 of the 40 hospitals EDs operating in Ireland in 2003-2008 were recorded according to standardised procedures. Data on sales of paracetamol-containing drugs to retail pharmacies for the period 1998-2008 were obtained from IMS Health. RESULTS: The withdrawal of distalgesic from the Irish market resulted in an immediate reduction in sales to retail pharmacies from 40 million tablets in 2005 to 500,000 tablets in 2006 while there was a 48% increase in sales of other prescription compound analgesics. The rate of IDO presentations to hospital involving distalgesic in 2006-2008 was 84% lower than in the three years before it was withdrawn (10.0 per 100,000). There was a 44% increase in the rate of IDO presentations involving other prescription compound analgesics but the magnitude of this rate increase was five times smaller than the magnitude of the decrease in distalgesic-related IDO presentations. There was a decreasing trend in the rate of presentations involving any paracetamol-containing drug that began in the years before the distalgesic withdrawal. CONCLUSIONS: The withdrawal of distalgesic has had positive benefits in terms of IDO presentations to hospital in Ireland and provides evidence supporting the restriction of availability of means as a prevention strategy for suicidal behaviour.

Relative toxicity of analgesics commonly used for intentional self-poisoning: A study of case fatality based on fatal and non-fatal overdoses.

BACKGROUND: Analgesics are used most frequently in fatal and non-fatal medicinal self-poisonings. Knowledge about their relative toxicity in overdose is important for clinicians and regulatory agencies. METHODS: Using data for 2005-2012 we investigated case fatality (number of suicides relative to number of non-fatal self-poisonings) of paracetamol, aspirin, codeine, dihydrocodeine, tramadol, paracetamol with codeine (co-codamol), paracetamol with dihydrocodeine (co-dydramol), ibuprofen and co-proxamol (paracetamol plus dextropropoxyphene; withdrawn in the UK in 2008 due to high toxicity). Data on suicides obtained from the Office for National Statistics and on non-fatal self-poisonings from the Multicentre Study of Self-harm in England. Case fatality was estimated for each drug, using paracetamol as the reference category. RESULTS: Compared to paracetamol and based on single drug deaths the case fatality index of dihydrocodeine was considerably elevated (odds ratio (OR) 12.81, 95% Confidence Interval (CI) 10.19-16.12). Case fatality indices for tramadol (OR 4.05, 95% CI 3.38-4.85) and codeine (OR 2.21, 95% CI 1.81-2.70) were also significantly higher than for paracetamol. The results when multiple drug deaths were included produced similar results. The relative toxicity of co-proxamol far exceeded that of the other analgesics. LIMITATIONS: Data on fatal self-poisonings were based on national data, whereas those for non-fatal poisonings were based on local data. CONCLUSIONS: Dihydrocodeine and tramadol are particularly toxic in overdose and codeine is also relatively toxic. They should be prescribed with caution, particularly to individuals at risk of self-harm.

Co-proxamol withdrawal has reduced suicide from drugs in Scotland.

AIM: To determine what effect the withdrawal of co-proxamol from the UK market has had on mortality from poisoning in Scotland. METHODS: This was a retrospective, observational study of mortality relating to poisoning by single agents in Scotland for the period 2000-2006. Mortality data were obtained from the General Register Office Scotland, and primary care prescribing data from the Information and Statistics Division of the Scottish Executive Health Department. RESULTS: A significant reduction in the proportion of poisoning deaths due to co-proxamol was observed following legislation [mean 2000-2004, 37 deaths (21.8% of total poisoning deaths); 2006, 10 (7.8%); P < 0.0001]. The most significant reduction was seen in male out-of-hospital deaths [mean 2000-2004, 17 (21.8%); 2006, two (2.9%); P < 0.0001]. This was associated with a decline in prescriptions by 60% within 6 months of legislation. The total number of poisoning deaths also fell, slightly earlier than the full impact on co-proxamol deaths (mean 2000-2004, 171.2; mean 2005-2006, 129.5; P = 0.005). CONCLUSIONS: Legislation has resulted in a major reduction in the number of deaths associated with co-proxamol poisoning in Scotland, with no compensatory rise in mortality from poisonings from other common analgesics. We estimate from this study that a minimum of 300 lives across the UK will have been saved by the withdrawal of co-proxamol.

Marked QRS complex abnormalities and sodium channel blockade by propoxyphene reversed with lidocaine.

The opiate analgesic propoxyphene produces cardiac toxicity when taken in overdose. We recently observed a patient with propoxyphene overdose in whom marked QRS widening was reversed by lidocaine. The reversal is apparently paradoxical as both agents block the inward sodium current (INa). We examined possible mechanisms of the reversal by measuring INa in rabbit atrial myocytes during exposure to propoxyphene and the combination of propoxyphene and lidocaine (60 and 80 microM, respectively). Propoxyphene caused use-dependent block of INa during pulse train stimulation. Block recovered slowly with time constants of 20.8 +/- 3.9 s. Block during lidocaine exposure recovered with time constants of 2-3 s. During exposure to the mixture, block recovered as a double exponential. The half time for recovery during exposure to the mixture was 1.6 +/- .9 s compared with a half-time of 14.3 +/- 2.9 s during exposure to propoxyphene alone. During pulse train stimulation, less steady-state block was observed during exposure to the mixture than during exposure to propoxyphene alone when the interval between pulses was greater than 0.95 s. Both drugs compete for a common receptor during the polarizing phase. The more rapid dissociation of lidocaine during the recovery period leads to less block during the mixture than during exposure to propoxyphene alone. The experiments suggest a mechanism for reversal of the cardiac toxicity of drugs which have slow unbinding kinetics.

Restrictions in means for suicide: an effective tool in preventing suicide: the Danish experience.

Restriction of means for suicide is an important part of suicide preventive strategies in different countries. The effect on method-specific suicide rate and overall suicide rate of restrictions on availability of carbon monoxide, barbiturates, and dextropropoxyphene was examined. From 1970 to 2000, overall suicide mortality and method-specific suicide mortality in Denmark were compared with official information about availability of barbiturates and analgesics and carbon monoxide in vehicle exhaust and household gas. Restrictions on availability of household gas with carbon monoxide content and barbiturates was associated with a decline in the number of suicides and suicides by self-poisoning with these compounds after controlling for the effect of calender year. Restricted access occurred concomittantly with a 55 percent decrease in suicide rate.

Fatal poisonings involving propoxyphene before and after voluntary withdrawal from the United States' market: An analysis from the state of Florida.

The synthetic opioid propoxyphene was a schedule IV controlled substance with multiple reported health risks before the US Food and Drug Administration issued a request for voluntary market withdrawal in November 2010. The purpose of this study is to investigate the characteristics and occurrences of propoxyphene-related deaths in Florida before and after voluntary market removal. Decedent-level toxicology data from Florida's Medical Examiners Commission was used to compare the temporal, polysubstance use, sociodemographic, and geographic profiles associated with propoxyphene-involved deaths for a pre-withdrawal (November 2008-November 2010) and post-withdrawal (December 2010-December 2012) period. Sensitivity analyses using multiple data sources, including Florida's Prescription Drug Monitoring Program and other states' data, were conducted to examine potential reporting bias. Results showed that the number of propoxyphene-involved deaths declined by 84% from 580 deaths to 92 deaths after market withdrawal. The co-occurrence of other prevalent drugs, such as oxycodone (17.2% to 26.1%, p=0.0422) increased significantly in the post-withdrawal study period. A larger proportion of the propoxyphene-related deaths were reported from South Florida after the withdrawal (28.4% to 56.5%, p<0.0001). No significant changes in age and race/ethnicity were observed. Sensitivity analyses revealed that several deaths occurred in other states after market withdrawal, as recently as 2016. Our findings are consistent with previous studies that propoxyphene was still available after removal from the US market. Continued surveillance is recommended after highly abused opioids are withdrawn from the market due to on-going safety risks.

Co-proxamol and suicide: preventing the continuing toll of overdose deaths.

Restricting means for suicide is a key element in suicide prevention strategies of all countries where these have been introduced. Preventing deaths from analgesic overdoses is highlighted in the National Suicide Prevention Strategy for England. The problem of self-poisoning with the prescription-only drug co-proxamol (dextropropoxyphene plus paracetamol) has received attention in several countries. We have conducted a review of the international literature related to possible strategies to tackle this problem. In England and Wales in 1997-1999, 18% of drug-related suicides involved co-proxamol; these constituted 5% of all suicides. Death usually results from the toxic effects of dextropropoxyphene on respiration or cardiac function. Death from co-proxamol overdose may occur rapidly, the lethal dose can be relatively low, and the effects are potentiated by alcohol and other CNS depressants. The majority of co-proxamol overdose deaths occur before hospital treatment can be received. The risk can extend to others in the household of the person for whom the drug is prescribed. While there is limited evidence that educational strategies have been effective in reducing deaths from co-proxamol poisoning, initiatives in Scandinavia, Australia and the UK to restrict availability of co-proxamol have produced promising results. Given the paucity of evidence for superior therapeutic efficacy of co-proxamol over other less toxic analgesics, there are good reasons to question whether it should continue to be prescribed.

ECG abnormalities in co-proxamol (paracetamol/dextropropoxyphene) poisoning.

OBJECTIVES: 1) To investigate ECG changes following co-proxamol (paracetamol 325 mg and dextropropoxyphene 32.5 mg) overdose in comparison to co-codamol (paracetamol and codeine) or co-dydramol (paracetamol and dihydrocodeine) in a prospective study. 2) To examine the relationship between estimated dextropropoxyphene dose and ECG changes in a larger patient population. BACKGROUND: Co-proxamol is a common cause of drug-induced death and hospital admission in the United Kingdom. ECG changes following dextropropoxyphene have been reported in animals and man, including QRS prolongation. METHODS: The prospective study was conducted on 15 patients and controls with overdose. A retrospective study of a cohort of 159 co-proxamol overdoses from a combined data set from Edinburgh and Newcastle, Australia was also conducted. The measured or estimated "four hour" plasma paracetamol level was used as a surrogate of the amount of dextropropoxyphene ingested. RESULTS: In the prospective study co-proxamol overdose caused statistically significant QRS prolongation (mean [95% CI] 99.36 [96.19, 102.53] msec), compared to the other combination opioid-paracetamol products (82.84 [80.81, 84.88] msec) but no effect on PR or QTc. QRS duration increase was evident soon after exposure and remained prolonged and stable over the following 24 h. In the retrospective cohort study a dose dependency of effect on QRS was documented, although the correlation coefficient relating paracetamol level to effect was relatively weak (r = 0.338, Sig. [2-tailed] 0.003, n = 74). CONCLUSIONS: QRS is significantly prolonged in co-proxamol overdose, and this prolongation is dose dependent. These findings have clinical relevance to the management of patients with co-proxamol poisoning.

Relation of postmortem blood alcohol and drug concentrations in fatal poisonings involving amitriptyline, propoxyphene and promazine.

Drugs and alcohol often occur together in fatal poisonings, complicating the process of determining the cause of death. Especially when found in concentrations generally regarded as toxic but not lethal, the question arises whether the combination of sublethal amounts was the likely cause of death. In this study, we examined poisoning deaths involving amitriptyline, propoxyphene and promazine, which are, after benzodiazepines, the most frequently occurring drugs in Finnish alcohol-related poisonings. From the forensic toxicology database, covering the years 1995-2002, we extracted 332 fatal poisonings, calculated median blood alcohol and drug concentrations, constructed concentration-concentration and concentration-response curves and evaluated the significance of the presence of therapeutic amounts of benzodiazepines. Median amitriptyline and propoxyphene concentrations were lower in alcohol-related cases than in clean drug poisonings. Correspondingly, the median blood alcohol concentrations in all drug-related poisonings were 1.5-2.2 mg/g lower than that found in clean alcohol poisonings. Alcohol concentration proved to be a more sensitive indicator of alcohol-drug interaction than drug concentration. This result suggests that when alcohol is present, relatively small overdoses of the studied drugs may result in fatal poisoning. In this context, fatal drug and alcohol concentrations and the issue of determining the most important agent in fatal drug-alcohol intoxications are discussed.

Hemodialysis in an infant with propoxyphene intoxication.

A 10-month-old infant was treated with intensive supportive care and hemodialysis for severe propoxyphene intoxication. Dialysis clearance studies demonstrated that propoxyphene was removed from the serum at approximately 50% of the rate of blood urea nitrogen removal. Possibly because of tissue binding of the drug, the absolute quantity of propoxyphene removed by dialysis was small. The child survived the acute episode of intoxication but died of pulmonary complications several days later. The role of dialysis in propoxyphene intoxication remains to be established.

Dextropropoxyphene overdosage. Pharmacological considerations and clinical management.

Dextropropoxyphene is a widely prescribed synthetic opiate-like drug of uncertain analgesic efficacy which, in acute overdosage, manifests all the features of opiate toxicity. It is rapidly absorbed and, in association with other central nervous system depressants such as alcohol or benzodiazepine drugs, may be rapidly fatal. Seriously overdosed patients are comatose with respiratory depression, vomiting, seizures and circulatory collapse; small pupils are a useful diagnostic marker. The first priority is to establish the airway and treat convulsions, if present. All the features of overdosage are then rapidly and safely reversed by the specific opiate antagonist naloxone given intravenously. High tissue concentrations and slow elimination of dextropropoxyphene metabolites make continued and intensive monitoring after resuscitation essential because sudden unpredictable deterioration may occur for up to 24 hours. Other more slowly toxic co-ingestants such as paracetamol (acetaminophen) are often present and should be detected and treated as necessary. Dextropropoxyphene poisoning is now probably one of the most common causes of self-poisoning death because, although there is an effective antidote, subjects frequently succumb before treatment can be made available.

Arthrogryposis multiplex congenita and bilateral mid-brain infarction following maternal overdose of co-proxamol.

We report a case of arthrogryposis multiplex congenita secondary to fetal hypokinesia in a 41-week gestation infant following antenatal central nervous system injury. The mother's pregnancy was complicated by an episode of attempted self harm, with an overdose of co-proxamol at 22 weeks of gestational age, and by the use of cocaine in combination with excess alcohol intake. Magnetic resonance imaging showed bilateral mid-brain cysts and marked atrophy of the basal ganglia and thalami.

Warning note on a blood gas report leading to diagnosis of acetaminophen overdose.

OBJECTIVE: To report a case of acetaminophen toxicity diagnosed after a warning note of "interfering substances" on the blood gas report, leading to early and successful treatment. DESIGN: Case report. SETTING: Tertiary-care pediatric intensive care unit. PATIENT: A 14-yr-old boy admitted unconscious with lactic academia and hyperglycemia. INTERVENTIONS: Routine investigations. MEASUREMENTS AND MAIN RESULTS: His initial investigations revealed hyperglycemia and lactic acidosis. An annotation of "interfering substances" on the blood gas report prompted us to investigate for toxic substances, and an acetaminophen overdose was confirmed. CONCLUSIONS: A persistent warning note on the blood gas report of a sick child with elevated lactate and glucose should alert the clinician to the possibility of an acetaminophen overdose.

Death due to dextropropoxyphene: Copenhagen experiences.

A review of 323 fatal poisonings with dextropropoxyphene is presented. The falling tendency of the poisoning in question and the National Board of Health's attention towards it are discussed.

The prevalence of dextropropoxyphene in autopsy blood samples.

The prevalence of dextroproxyphene (DXP) in the total medico-legal autopsy material in Sweden during 1992 to 1996 was examined. Simultaneous findings of paracetamol and alcohol in the blood were considered in the analyses. DXP in peripheral blood was found in 1782 (7.5%) of the 23,691 cases analysed during 1992-1996. The autopsy prevalence of DXP increased by 25% from 1992 to 1996. The mean blood DXP concentration was 1.62 micrograms/g (the blood level of DXP after a therapeutic dose is 0.05-0.75 microgram/g). The blood DXP level was < 0.75 microgram/g in 947 cases and > or = 0.75 microgram/g in 835 cases. The cases < 50 years of age had a significantly higher mean concentration (2.36 micrograms/g) than those > or = 50 years (1.04 micrograms/g). Paracetamol in the blood was found in 53% of the DXP cases (mean 75.0 micrograms/g; therapeutic level 2.5-25 micrograms/g) and alcohol in 43% (mean level 0.14%). According to the death certificates 54% (956) died from fatal poisoning. Among these, 74% (707) showed a blood DXP concentration > or = 0.75 microgram/g. Other Scandinavian countries, Denmark and Norway have reduced the rate of fatal DXP poisonings through government regulations for prescription. As the defined daily dose/1000 inhabitants during a 12-month period (DDD) of DXP preparations in Sweden (14.4 in 1996) is six times as high as in Denmark and nine times as high as in Norway, introduction of similar regulations in Sweden should be considered.

The manner of death among fatalities where dextropropoxyphene caused or contributed to death.

Dextropropoxyphene (DXP) is one of the most prescribed analgesic compounds in Sweden. To investigate the manner of death among fatalities where DXP caused or contributed to death all medico-legal autopsies performed in Sweden in 1992-1996 were analysed on the bases of toxicological analyses and death certificates. DXP in peripheral blood was found in 1782 (7.5%) of the total 23,691 blood samples. According to the death certificates 956 (54%) of the 1782 cases were classified as fatal DXP poisoning. Among these, the manner of death was classified as accidental in 49 cases (5%), suicidal in 542 cases (57%) and undetermined in 365 cases (38%). The reported manner of death differed between the six forensic medicine districts in Sweden. The accident rate differed significantly between the district with the highest rate (9%) and the districts with the lowest rate (1%). One district had a significantly higher incidence of suicide (73%) than four of the other districts, while another district had a significantly lower incidence of suicide (33%) than all the other districts. The accident classification rate among the physicians performing ten or more autopsies varied from 0% to 17%, the suicide classification rate from 25% to 83% and the rate of undetermined manner of death from 8% to 71%. A major conclusion drawn from this study is that accidental DXP fatalities may be underestimated. This may have serious consequences, as under-reporting of accidental DXP fatalities will increase the risk that knowledge of the high toxicity of DXP will not reach the population consuming this drug. Since valid death statistics concerning the manner of death at DXP fatalities are needed to provide the base for preventive actions, special attention should be paid to the classification process, in order to increase the uniformity of the assessments among the different physicians, and to avoid under-reporting of accidents.