Four-hour acetaminophen concentration estimation after ingested dose based on pharmacokinetic models

INTRODUCTION

The United Kingdom has recently changed the indications for N-acetylcysteine treatment for acetaminophen intoxication. Any ingestion over 75 mg/kg is now referred to the hospital. A model based on pharmacokinetic parameters was developed to predict 4-h acetaminophen concentration for this and other ingested doses.

METHODOLOGY

EMBASE and Medline were searched to obtain values for volume of distribution, absorption, and elimination constants and bioavailability for acetaminophen. Four-hour concentrations were calculated for ingestion doses currently recommended for hospital referral in different countries. Calculated plasma concentrations at 4 h for several doses were plotted against the Rumack-Matthew and the United Kingdom treatment lines.

RESULTS

Six articles were used for the calculations (4 adult and 2 pediatric). In order to achieve a 4-h acetaminophen concentration of 100 mg/L, doses (mg/kg ± 99.9CI) of 180.5 ± 43.2 for adults and 396.1 ± 115.5 for children were calculated.

DISCUSSION

A dose of 75 mg/kg would likely yield a 4-h acetaminophen concentrations well below 100 mg/L. Medical toxicologists and poison information specialists are left without evidence-based guidance for which patients or which ingestion history would now warrant referral to hospital for acetaminophen concentration measurement. Larger toxicokinetic studies in acetaminophen overdose are needed to define ingestion dose for referral to hospital.

Treating acetaminophen overdose: thresholds, costs and uncertainties

The United Kingdom's Medicines and Healthcare Products Regulatory Agency (MHRA) modified the indications for N-acetylcysteine therapy of acetaminophen (paracetamol) overdose in September 2012. The new treatment threshold line was lowered to 100 mg/L (662 μmol/L) for a 4 hours acetaminophen concentration from the previous 200 mg/L (1325 μmol/L). This decision has the potential to substantially increase overall costs associated with acetaminophen overdose with unclear benefits from a marginal increase in patients protected from hepatotoxicity, fulminant hepatic failure, death, or transplant. Changing the treatment threshold for acetaminophen overdose also implies that ingestion amounts previously thought not to require acetaminophen concentration measurements would need to be revised. As a result, more individuals will be sent to hospitals in order that everyone with a predicted 4 hours concentration above the 100 mg/L line will have concentrations measured and potentially be treated with N-acetylcysteine. Before others consider adopting this new treatment guideline, formal cost-effectiveness analyses need to be performed to define the appropriate thresholds for referral and treatment.

Digital mobile telephones and interference of ophthalmic equipment

AIM

To assess the effect of mobile telephone electromagnetic interference on electronic ophthalmic equipment.

METHODS

Prospective audit with mobile telephones placed at distances of 3 m, 1 m, and 30 cm from, and in contact with, electronic ophthalmic equipment. Any interruption or cessation of the function of the ophthalmic device was assessed with the mobile telephones in standby, and in dialling or receiving modes. Any alterations of displayed digital figures or numbers were also assessed.

RESULTS

A total of 23 electronic ophthalmic devices in two hospital ophthalmology outpatient departments were evaluated. All six mobile telephones used, and 22 (95.7%) of the 23 ophthalmic equipment evaluated had the Conformité Européene (CE) mark. No device showed any interruption or cessation of function. There were no alterations of displayed digital figures or numbers. The only effect of any kind was found with four instruments (1 non-CE marked), where there was temporary flickering on the screen, and only occurred when the mobile telephones were dialling or receiving at a distance of 30 cm or less from the instruments.

CONCLUSION

This study shows that among the electronic ophthalmic devices tested, none suffered failure or interruption of function, from mobile telephone interference. Although not comprehensive for all ophthalmic equipment, the results question the need for a complete ban of mobile telephones in ophthalmic departments. It highlights the need for a controlled, objectively measured study of the clinically relevant effects of mobile telephones in the ophthalmology outpatient setting.

Treatment of anticholinergic-induced ileus with neostigmine

A 33-year-old man with a history of recreational benztropine abuse presented to the emergency department with confusion, abdominal pain, and distention. An abdominal radiograph revealed gross fecal loading. He was initially treated with intravenous fluids and opiate analgesia. Subsequently, a diagnosis of anticholinergic poisoning was made, based on tachycardia, delirium, dry mucosa, and reduced bowel sounds. Treatment with tacrine reversed the delirium, and a history of repeated benztropine use was obtained. Persistent ileus was treated with repeated doses of neostigmine, and gastrointestinal motility returned with prompt defecation. Neostigmine appears to be useful in reversing ileus caused by anticholinergic drug overdose. Theoretically, it may be useful in reversing anticholinergic ileus resulting from acute drug overdose, allowing or enhancing decontamination, but the safety and potential efficacy of neostigmine in this scenario have not been established.

Patterns of dental enamel defects at ancient Mendes, Egypt

The dental remains of 88 individuals from Old Kingdom, First Intermediate, and Greco-Roman periods at the ancient Egyptian site of Mendes (Tell er-Rub(c)a) were examined for dental enamel hypoplasia, and the results reported here provide some of the first comparative data on enamel defects in ancient Egypt. Overall, 48% of the individuals in the sample have one or more teeth with hypoplasia, with 17% of permanent teeth and 8% of deciduous teeth affected. The permanent teeth account for 87% of the total number of affected teeth, a prevalence over deciduous teeth that is significant at alpha = 0.05. Permanent and deciduous teeth display different patterns of hypoplasia, with the former exhibiting both discrete pitting and linear furrowing, and the latter exhibiting only pits. Teeth with linear defects significantly outnumber those with pits by a factor of more than three to one. Only permanent canines display more than one lesion on a tooth, with a mean of 1.4 defects per affected tooth. Although calculation of the age of insult from lesion position is imprecise, it appears that stress episodes occurred most commonly between approximately 3-5 years of age. The presence of pits in the deciduous dentition, however, suggests that physiological stresses began in utero. There is no statistically significant difference in the frequency of enamel defects between males and females. An observed decrease in the frequency of defects from the Old Kingdom period to the subsequent First Intermediate and Greco-Roman periods is not significant at alpha = 0.05, although such a decrease is expected given epigraphic and other data that refer to prolonged drought and malnutrition in the late Old Kingdom. The calculated chi(2) value of 3.83 is significant at the 0.10 level, however, and since our sample is rather small and the magnitude of the chi-square statistic is a function of sample size, we recommend that future research investigate further the relationship between the frequency of enamel defects and the time period in which they occur.

Consumption of non-steroidal anti-inflammatory drugs and the development of functional renal impairment in elderly subjects. Results of a case-control study

AIMS

The aim of the present study was to explore the level of risk associated with community use of non-steroidal anti-inflammatory drugs (NSAIDs).

METHODS

We carried out a matched case-control study of the relationship between recent use of NSAIDs and the presence of functional renal impairment present at the time of hospitalisation with a range of clinical problems. Cases (n = 110) were consecutive patients admitted acutely to hospital who had serum creatinine levels greater than or equal to 0.15 mmol l(-1) , which improved by 20% or more within the next 14 days, or prior to discharge from hospital. Controls (n= 189) were subjects of the same sex and age (to within 5 years) as the cases, who were admitted to the same hospital, who had normal serum creatinine levels (<0.12 mmol l(-1) throughout their hospital stay. Information on a number of study factors, including recent use of aspirin and other NSAIDs, was obtained by structured interview.

RESULTS

Overall, there was a weak association between consumption of NSAIDs (including non-prophylactic aspirin) and the development of functional renal impairment-adjusted odds ratios (OR) with use of NSAIDs in the previous week or in the previous month: OR 1.5 (95% CI 0.80, 2.9) and 1.8 (95% CI 0.97, 3.4) respectively. In subjects with a previous history of renal disease the adjusted OR was 6.6 (0.75, 57.8) and in those with a history of gout or hyperuricaemia the OR was 7.2 (1.3, 40.2). There was a weak positive relationship between the dose of drug consumed in the previous week and the odds of functional renal impairment. The relationship between risk and published figures for drug half-lives (t1/2) was stronger. The odds ratio increased from 1.2 (95% CI 0.61, 2.4) with a t1/2 < or = 4 h, to 4.8 (1.5, 15.8) with a t1/2 of < or = 12 h (P=0.012, test for trend). This relationship remained statistically significant after adjustment for a number of clinical variables and the dose of drug ingested.

CONCLUSIONS

NSAIDs are an important cause of functional renal impairment in subjects with renal disease or a history of gout or hyperuricemia. The half-life of the drug is more important than the ingested dose in determining the risk of this outcome. Long half-life drugs should be avoided in individuals who are at risk of developing renal impairment.

Intravenous thiodan (30% endosulfan in xylene)

OBJECTIVE

We report the first case of intravenous self-poisoning with Thiodan (30% endosulfan in xylene).

CASE REPORT

A 28-year-old woman with a past history of epilepsy presented with refractory grand mal seizures after injecting 1 mL of Thiodan intravenously. She developed liver dysfunction, proximal myopathy secondary to rhabdomyolysis and renal failure.

INTERVENTIONS AND OUTCOMES

The seizures were terminated with midazolam and thiopentone. Mechanical ventilation was required for nine days. Renal and liver dysfunction resolved with supportive measures only. Hemodialysis was not required. Pulmonary complications and neurological sequelae were minimal with the patient making a full recovery over three months.

CONCLUSION

The intravenous adminis-tration of a small dose of endosulfan in xylene caused the rapid onset of severe grand mal seizures. The absence of pulmonary edema in this case suggests aspiration to be the cause of pulmonary toxicity due to oral endosulfan poisoning.

Bilateral serous retinal detachments in the H.E.L.L.P. syndrome

The first case of the H.E.L.L.P. syndrome with ophthalmic signs is described. This syndrome of pregnancy is characterized by Haemolysis, Elevated Liver enzymes and Low Platelets in association with upper abdominal pain. Diagnosis and treatment is often delayed, while a non-obstetric cause for these findings is sought. The present report adds serous retinal detachments in association with sub-retinal opacities to the signs which should raise suspicion of this syndrome.

Propranolol steady-state pharmacokinetics are unaltered by omeprazole

In a randomised double-blind cross-over study, 8 normal subjects received propranolol 80 mg twice daily with omeprazole 20 mg or identical placebo each morning. Propranolol kinetics were measured on day 8 of both treatment periods. Areas under the propranolol concentration/time curves were not significantly increased by omeprazole treatment: off treatment mean 787.6, on treatment 802.5 ng-1.ml.h. Maximum and minimum steady-state propranolol concentrations were similarily unaffected. Omeprazole also failed to increase the clinical effect of propranolol, as assessed by exercise tests on Day 8 of treatment. We conclude that omeprazole in the dose likely to be used for peptic ulcer has no significant effect on the kinetics or action of propranolol.