IMPACT OF LEGISLATIVE CHANGES ON PATTERNS OF ANTIPSYCHOTIC PRESCRIBING AND SELF-POISONING IN SCOTLAND: 2000-06

Association between Prescribing and Intoxication Rates for Selected Psychotropic Drugs: A Longitudinal Observational Study

Psychotropic prescription drugs are commonly involved in intoxication events. The study's aim was to determine a comparative risk for intoxication in relation to prescribing rates for individual drugs. This was a nationwide observational study in Slovenian adults between 2015 and 2021. Intoxication events with psychotropic drugs were collected from the National Register of intoxications. Dispensing data, expressed in defined daily doses, were provided by the Health Insurance Institute of Slovenia. Intoxication/prescribing ratio values were calculated. The correlation between trends in prescribing and intoxication rates was assessed using the Pearson correlation coefficient. In total, 2640 intoxication cases with psychotropic prescription drugs were registered. Anxiolytics and antipsychotics were the predominant groups. Midazolam, chlormethiazole, clonazepam, sulpiride, and quetiapine demonstrated the highest risk of intoxication, while all antidepressants had a risk several times lower. The best trend correlation was found for the prescribing period of 2 years before the intoxication events. An increase of 1,000,000 defined daily doses prescribed resulted in an increase of fifty intoxication events for antipsychotics, twenty events for antiepileptics, and five events for antidepressants. Intoxication/prescribing ratio calculation allowed for a quantitative comparison of the risk for intoxication in relation to the prescribing rates for psychotropic drugs, providing additional understanding of their toxicoepidemiology.

Effects of MHRA drug safety advice on time trends in prescribing volume and indices of clinical toxicity for quinine

AIMS

To ascertain the effects of the Medicines and Healthcare products Regulatory Agency's (MHRA) safety update in June 2010 on the volume of prescribing of quinine and on indices of quinine toxicity.

METHODS

We analysed quarterly primary care total and quinine prescribing data for England and quinine prescribing volume for individual Primary Care Trusts in the North East of England from 2007/8 to 2011/12 obtained from the ePACT.net database. We also analysed quinine toxicity enquiries to the National Poisons Information Service (NPIS) via Toxbase(®) and by telephone between 2004/5 and 2011/12. Joinpoint regression and Pearson's correlation tests were used to ascertain changes in trends in prescribing and indices of toxicity and associations between prescribing and indices of toxicity, respectively.

RESULTS

Total prescribing continued to increase, but annual growth in quinine prescribing in England declined from 6.0 to -0.6% following the MHRA update [difference -0.04 (95% confidence interval -0.07 to -0.01) quinine prescriptions per 100 patients per quarter, P = 0.0111]. Much larger reductions were observed in Primary Care Trusts that introduced comprehensive prescribing reviews. The previously increasing trend in Toxbase(®) quinine searches was reversed [difference -19.76 (95% confidence interval -39.28 to -9.20) user sessions per quarter, P = 0.0575]. Telephone enquiries to NPIS for quinine have declined, with stabilization of the proportion of moderate to severe cases of quinine poisoning since the update.

CONCLUSIONS

The MHRA advice was followed by limited reductions in the growth in quinine prescribing and in indicators of quinine overdose and toxicity. Quinine prescribing, however, remains common, and further efforts are needed to reduce availability and use.

Impact of amending the acetylcysteine marketing authorisation on treatment of paracetamol overdose

In September 2012, the Medicines and Healthcare products Regulatory Agency (MHRA) substantially amended the Marketing Authorisation for acetylcysteine following an extensive review. The present study examined the impact of this license change on patterns of acetylcysteine use in patients presenting to hospital after paracetamol (acetaminophen) overdose. Between September 2011 and April 2013, 785 consecutive patients presented to York Hospital due to paracetamol overdose, and a before-after analysis was used to compare outcomes. There were 483 patients before and 302 patients after the license amendment, and age, gender, acute or staggered overdose pattern, and dose were similar in both groups. In the patients with paracetamol concentrations between the "100-line" and "200-line," a significantly higher proportion received acetylcysteine treatment (51% before versus 98% after, P = 0.0029), as expected. A modest increase was also observed in relation to late or staggered overdose or cases where the time of ingestion was uncertain (53% versus 74%, P = 0.0430). The median duration of hospital stay increased across the entire study population, from 15 to 24 hours (P = 0.0159) due to the increased proportion of patients requiring acetylcysteine treatment. The findings indicate that the MHRA amendment is a financially costly intervention, and further studies are needed to examine clinical outcomes so that its cost effectiveness might be addressed.

Unplanned alcohol withdrawal: a survey of consecutive admissions to an acute medical unit in 2010 and 2011

BACKGROUND

Alcohol-related presentations to hospital have been increasing in the UK in recent years, including the occurrence of acute withdrawal. This study sought to better characterize the clinical features, patterns of treatment and outcomes in this patient group.

METHODS

Patients admitted to the Acute Medical Unit of York Hospital due to acute alcohol withdrawal are normally treated according to a protocol that involves both fixed-dose and symptom-triggered drug administration. Admissions between 2010 and 2011 inclusive were studied.

RESULTS

There were 211 admission episodes solely due to acute alcohol withdrawal, involving 127 patients (97 men, 76.4%) with median age of 45 years (interquartile range: 39-52 years). There was a high prevalence of depression (34%), alcoholic liver disease (22%) and drug misuse (12%). Total dose of chlordiazepoxide varied between 0 and 610 mg and tapered rapidly after the first day of admission. Vitamin supplements were administered to >90% of patients, including parenteral and oral in 74%, parenteral alone in 9% and oral alone in 9%. A specialist alcohol nurse reviewed patients while in hospital in 40% of cases. Approximately one-third of patients had multiple admissions for alcohol withdrawal during the study period.

CONCLUSION

A high prevalence of physical and mental health disorders was observed. The local policy permitted high initial chlordiazepoxide doses and prompt downward titration, with a broad range of doses between individuals. Approximately 10% required no specific therapy, and there may be opportunities for developing alternative pathways for delivery of care in an ambulatory setting for these patients.

Comparative drug dose and drug combinations in patients that present to hospital due to self-poisoning

Self-poisoning is a common reason for acute presentation to hospital. Commonly involved drugs have been reported, but few data exist concerning the different combinations of agents or comparative doses ingested. The present study sought to better characterise the typical patterns of drug overdose that may present via the emergency department. Consecutive adults ≥16 years of age that presented to York Hospital owing to self-poisoning were studied for 2010-2011 inclusive. The primary outcome measure was reported dose, expressed as a multiple of the defined daily dose (DDD) to allow comparison between different agents. There were 1024 patients, including 622 women (60.7%), and median age was 32 years (range, 16 to 92 years). Overdose in men was associated with a higher overall quantity of drugs: arithmetic mean of 20 DDD multiples (95% CI, 15-26) versus 13 (11-15), p = 0.001. Overdose involved a single agent only in 538 patients (52.5%). The mean paracetamol dose was 4.0 (95% CI, 3.7-4.3) DDD multiples; the doses of antidepressants (19.4, 17.0-21.7, p < 0.0001) and benzodiazepines (18.0, 12.8-23.2, p < 0.0001) were comparatively higher. The types of agents involved in self-poisoning and common combinations of agents are characterised. Psychotropic medications were ingested in comparatively larger quantities than analgesic agents and had worse clinical outcome. Further work is required to understand the factors that determine the quantity of drug ingested in patients at risk of drug overdose so as to minimise the risk of significant toxicity.

Clinical toxicology and drug regulation: a United Kingdom perspective

The Medicines and Healthcare products Regulatory Authority (MHRA) is the government body with responsibility for regulating new and existing medicines and medical devices in the United Kingdom. The Yellow Card scheme is a well-established pharmacovigilance system that collects voluntary reports of adverse effects associated with therapeutic drug use. In contrast, data concerning clinical toxicological effects are more poorly characterised. No comparable surveillance processes exist in the United Kingdom or elsewhere in Europe that might allow systematic collection of clinical data and outcomes after drug overdose. Toxicological effects are normally ascertained from individual patient reports or small case series from a few specialised poisons units, so that these data are generally under-represented in post-marketing consideration of risks and benefits. Safety concerns may lead to withdrawal of the Marketing Authorisation or restricted prescribing conditions, which are conveyed to health care professionals by means of safety warnings. These may have a variable impact, and three selected examples are presented to illustrate the complex interaction between drug regulation and clinical toxicology. First, the effects of the withdrawal of rofecoxib in 2004 shows that regulatory responses may reduce the prescribing of drugs across a particular class, and this has resulted in fewer enquiries to Poisons Control Centres regarding all cyclooxygenase-2 selective inhibitors. Secondly, data concerning the impact of safety warnings about antipsychotic medications illustrate that regulatory decisions may have a variable impact due to other factors that influence prescribing, including clinical guidelines, marketing pressures, and lack of alternative safe medications. Finally, the recent withdrawal of co-proxamol serves as an example of how clinical toxicology data can inform the drug regulation process and improve safety by minimising the risk of death associated with overdose. Greater reliance on clinical toxicology data could better inform the drug regulation process, perhaps through coordinated data collection systems that already exist in certain national poisons centres. Routine collection of high quality data concerning the effects of drug overdose could allow a more comprehensive review of risk and benefit by the regulatory authorities.

Caffeine fatalities--do sales restrictions prevent intentional intoxications?

OBJECTIVE

Caffeine is widely available in beverages and in different over-the-counter products, including tablets containing 100 mg caffeine. Because intentional fatal intoxications with caffeine occur, the maximum quantity of caffeine tablets that can be bought over the counter in a single purchase was restricted from 250 to 30 in Sweden in the year 2004. The objective of this article was to study the effect of this decision on the number of fatal caffeine intoxications.

METHOD

In Sweden 95% of all cases undergoing forensic autopsy are screened for a number of drugs including caffeine. All cases during January 1993-September 2009 with a caffeine concentration above 80 microg/g blood were recorded.

RESULTS

During the study period toxicological investigations were performed in 83,580 forensic autopsies. Caffeine contributed to the fatal outcome in 20 cases (0.02%). Thirteen (65%) of these fatalities occurred before the introduction of the sales restriction. However, no fatal intoxications where caffeine contributed to the cause of death was recorded between May 2007 and September 2009.

CONCLUSION

Overdoses of tablets containing caffeine can be fatal, suicides as well as accidents occur. Restricting the maximum quantity of caffeine tablets available over the counter seemed to be effective in preventing suicides because of caffeine although some time elapsed until the effect was noted. Further monitoring is required to ensure that the observed lower caffeine mortality is a sustained effect.

Patterns of antiepileptic drug overdose differ between men and women: admissions to the Edinburgh Poisons Unit, 2000-2007

BACKGROUND AND AIMS

Antiepileptic drugs are increasingly used in patients with psychiatric disorders who are at increased risk of self-harm. This might increase the likelihood that these agents are used as a means of overdose. This study was designed to examine the rate of occurrence of antiepileptic drug overdose between 2000 and 2007.

METHODS

A retrospective observational study examined patterns of antiepileptic drug overdose in patients admitted to the Edinburgh Poisons Unit, and compared prescription data for the corresponding region. Data were compared using chi-square trend tests.

RESULTS

There were 18 010 admissions to the Toxicology Unit, and 613 patients ingested at least one antiepileptic drug (3.4%). The most frequently implicated were carbamazepine, sodium valproate, phenytoin and lamotrigine, which corresponded with those most commonly prescribed. Women were more likely to ingest lamotrigine than men (P < 0.0001), and less likely to ingest sodium valproate (P = 0.0234). Patients that ingested antiepileptic drugs were more likely to be admitted to hospital for >1 day (22% vs. 8%, P < 0.0001) and need transfer to a psychiatric facility (14% vs. 7%, P < 0.0001).

CONCLUSIONS

Patients that ingested antiepileptic drugs required more intensive medical and psychiatric intervention compared to ingestion of other agents. Significant gender differences were noted in the specific antiepileptic drug ingested. Further work is required to establish whether this discrepancy may be explained by gender-based prescribing practices.

Skin permeation and ex vivo skin metabolism of O-acyl haloperidol ester prodrugs

Ethyl (HE), propyl (HP), butyl (HB), octyl (HO) and decyl (HD) O-acyl esters of haloperidol (HA) were evaluated for permeation across full-thickness human and guinea pig skin. The inclusion of 0.5mgmL(-1) cetrimide as a receptor phase solubilising agent did not significantly alter the barrier properties of the membranes. The permeation of the parent drug, HA, across guinea pig skin was found to be greater than that of its derivatives. Prodrug hydrolysis by cutaneous esterases was minimal. The permeation of HE, HP and HB across freshly excised guinea pig skin was subsequently investigated, however, prodrug hydrolysis remained low. Hydrolysis studies using a skin extract revealed only limited prodrug metabolism. However, in the presence of a liver extract, hydrolysis of all prodrugs was rapid. It was proposed that GGGX esterases, required for the hydrolysis of tertiary esters, were not present at a sufficiently high concentration within the skin for substantial prodrug hydrolysis to occur. This does not necessarily detract from the system as post-transdermal delivery liberation of HA in vivo is an equally useful mode for delivering this drug to the systemic circulation.

Characteristics of drug-related hospital separations in Australia

BACKGROUND

To examine (a) numbers of alcohol and drug-related hospital separations, 1999-2005; (b) demographics of these separations; (c) principal diagnoses co-occurring with drug-related problems; (d) length of hospital stay.

METHODS

Data from the National Hospital Morbidity Database (NHMD) were analysed. Hospital separations where alcohol, opioids, amphetamine, cannabis, cocaine, other drugs (such as sedatives and hypnotics) and pharmaceutical poisoning were mentioned were examined.

RESULTS

Numbers per million persons were highest for alcohol, followed by other drugs, particularly sedatives and hypnotics. Alcohol and opioid-related problems were prominent among older age groups, whereas cannabis and pharmaceutical poisoning problems had greater proportions among 15-24 year olds. Opioid-related separations were relatively high in number within the context of prevalence of use, and often accompanied by principal diagnoses of physical or general health problems. Almost half of amphetamine and cannabis-related separations were accompanied by principal diagnoses of mental health problems.

CONCLUSIONS

This research highlights the complexities of drug-related hospital presentations, indicating the need for thorough assessment of physical and mental problems, as well as a drug use history at the time of admission. Continued development of integrated models of care, targeting both mental health and drug use are essential. Consistent with the international literature, many of these separations are preventable, particularly those for pharmaceutical poisoning. Finally, ongoing efforts to reduce the significantly greater harms related to opioid use, as well as increasing treatment opportunities for opioid-dependent people in Australia is an important public health priority.