Site to site variability of postmortem drug concentrations in liver and lung

We evaluated postmortem diffusion of gastric drug residue into tissues and blood in eight suicidal overdoses. Analyses were performed on liver (five sites), lung (four sites), spleen, psoas muscle and kidney (left and right), blood (peripheral and torso), vitreous, pericardial fluid, bile and, urine as well as residual gastric contents. Standard analytical techniques and instrumentation gas chromatograph/mass spectrometer and high performance liquid chromatography (GC-MS and HPLC) were used throughout. These case studies confirm previous studies of an animal and human cadaver model of gastric diffusion, in that in several instances there was drug accumulation in the left posterior margin of the liver and, to a lesser extent, the left basal lobe of the lung. Uncontrollable variables, such as postmortem interval, refrigeration before autopsy, and position of the body appear to influence significantly drug accumulation in a specific site. We suggest that autopsy sampling techniques should be standardized on blood taken from a ligated peripheral (preferably femoral or external iliac) vein, and liver from deep within the right lobe.

Late increase in acetaminophen concentration after overdose of Tylenol Extended Relief

We report a case demonstrating a late increase in acetaminophen concentration after ingestion of Tylenol Extended Relief (extended-release acetaminophen; McNeil Consumer Products) along with drugs known to slow gastrointestinal motility. Coingestants that slow gastrointestinal motility are known to affect the interpretation of serum drug concentrations. However, this case illustrates potentially significant differences between extended-release and immediate-release acetaminophen and demonstrates an exception to the current manufacturer recommendation for the use of the Rumack-Matthew nomogram in this setting.

Status epilepticus following intravenous N-acetylcysteine therapy

A previously healthy 2 1/2-year-old girl developed status epilepticus followed by cortical blindness during intravenous N-acetylcysteine therapy for paracetamol ingestion. The child's vision was almost completely recovered during the 18 months follow-up period. We assume that the cortical blindness was a postictal sequela after prolonged seizure episode, most probably due to respiratory depression induced by N-acetylcysteine.

Refining the level for anticipated hepatotoxicity in acetaminophen poisoning

Treatment of an acetaminophen overdose with N-acetyl cysteine usually is based on the position of the 4-h acetaminophen (APAP) level on the Rumack-Matthew nomogram; however, there is disagreement on the level at which clinically relevant hepatotoxicity occurs. A retrospective review of all acute adult formulation APAP exposures reported to our poison center between 1986 and 1993 was performed and cases corresponding to the "possible risk or toxicity" range on the nomogram were identified. Our current poison center protocol for APAP poisoning does not recommend treatment with N-acetylcysteine (NAC) in low-risk patients if the 4-h serum APAP level or the extrapolated equivalent falls within the possible toxicity range on the nomogram. Seventeen cases met the inclusion criteria for the study and received no NAC; six additional patients met inclusion criteria but received one or two doses of NAC before therapy was discontinued. No patients in either group demonstrated clinical evidence of hepatotoxicity. This pilot study suggests that patients with no risk factors and APAP levels in the "possible risk" range may not require NAC therapy.

Acetaminophen and salicylate serum levels in patients with suicidal ingestion or altered mental status

Is universal screening of acetaminophen (APAP) and salicylate (SAL) necessary in patients with a suicidal ingestion or an altered mental status and suspected ingestion? This descriptive, retrospective chart review in an emergency department in a large urban county hospital examined all patients who presented with a history of suicidal ingestion or an altered mental status with a strong suspicion of ingestion from January 1992 through October 1993. APAP and SAL serum levels were measured in 1,820 patients, and charts of patients with APAP serum levels of > 1 microgram/mL or SAL serum levels of > 1 mg/dL were reviewed. The patient's history of ingesting APAP or SAL was recorded, as well as the clinician's interpretation of that level. Sixteen charts were not available. APAP levels of > 1 microgram/mL were found in 175 (9.6%) patients, 120 (6.5%) of whom were APAP history-positive and 55 (3%) APAP history-negative. None of the APAP history-negative group required therapy with N-acetylcysteine. Eight (0.3%) of the APAP history-negative group had potentially toxic levels of > 50 micrograms/mL. SAL levels of > 1 mg/dL were found in 155 (8.5%) patients, 44 (2.5%) of whom were SAL history-positive and 111 (6%) SAL history-negative. Three patients were SAL history-negative but had a significant chronic SAL intoxication. All these patients presented with an altered mental status and had an anion gap of > 20 mEq/L. Universal screening found that 0.3% of suicidal ingestions had a potentially toxic APAP intoxication not suggested by history. This incidence of infrequent but potentially life: threatening overdose should prompt clinicians to screen all of their patients with a suspected ingestion. Salicylate screening found that 0.16% of suicidal ingestions had a toxic SAL intoxication not suggested by history, although such intoxication should be suggested by an elevated anion gap and an altered mental status. Since this less severe intoxication is less frequent and usually suggested by commonly obtained laboratory data, universal screening is not indicated, but a more selective approach to screening could be taken.

[Clinical-toxicological case (1). Dosage of N-acetylcysteine in acute paracetamol poisoning]

There are currently three protocols used for the administration of N-acetylcysteine in the treatment of acute paracetamol poisoning. In the USA only the oral protocol is approved, while in Europe an intravenous protocol is used. If treatment is started within 10 h. after paracetamol ingestion, all three protocols appear to be equally effective. If treatment is started 10 to 24 h. after the ingestion, the oral protocol and the Smilkstein protocol appear to be superior to the Prescott protocol. N-acetylcysteine is effective also when started more than 15 h after the ingestion. Patients who present with liver failure after paracetamol poisoning should be treated with a prolonged course of N-acetylcysteine.

Expression of liver-specific functions in rat hepatocytes following sublethal and lethal acetaminophen poisoning

AIM

In order to study the short-term effect of moderate and severe reduction of liver function by acetaminophen poisoning of different severity on gene expression for liver-specific functions, rats were given 3.75 and 7.5 g per kg body weight acetaminophen intragastrically. The lower dose is associated with low mortality; after the higher dose, most rats die at between 12 and 24 h.

METHODS

In the morning, 1 1/2, 3, 6, 9, and 12 h after the injection, the rats were killed and RNA was extracted from liver tissue. By slot-blot hybridization mRNA steady-state levels were determined for enzymes involved in metabolic liver functions, i.e. ureagenesis, gluconeogenesis, and drug metabolism, for acute phase proteins, "house-keeping" proteins, and for proteins related to liver regeneration. Results were expressed as per cent of the level in similarly fasted, untreated rats of the same stock

RESULTS

After the smaller dose of acetaminophen, most of the examined mRNA levels were increasing during the experimental period, being two- to four-fold elevated in relation to control after 6 to 12 h. Rats receiving the lethal dose either showed no or a later and smaller increase, and in several cases a fall towards the end of the experiment. The greatest differences were seen for mRNA of arginase, beta-fibrinogen, alpha 1-acid glycoprotein, alpha-tubulin, histone 3, TGF beta, and cyclin d, i.e. proteins associated with acute phase response and liver cell replication and maintenance.

CONCLUSIONS

It is concluded that reversible intoxication with acetaminophen induces an adaptive modulation of mRNA expression of liver functions and regeneration which is lacking after severe intoxication. This adaptation, with emphasis on acute phase response and regeneration, may be crucial for recovery after acetaminophen intoxication. If this also applies to the intoxication in man, estimates of the corresponding variables may be clues to the prognosis of acetaminophen-induced fulminant hepatic failure.

A pharmacokinetic comparison of acetaminophen products (Tylenol Extended Relief vs regular Tylenol)

OBJECTIVE

To compare the pharmacokinetics of Tylenol Extended Relief (ER APAP) with those of immediate-release acetaminophen (IR APAP) at supratherapeutic doses.

METHODS

A prospective, double-blind, randomized, crossover comparison trial involving 14 adult volunteers. Each subject ingested 75 mg/kg of either ER APAP or IR APAP and 1 week later received the other APAP preparation. On both occasions plasma APAP concentration ([APAP]) was determined 0.5, 1, 2, 3, 4, 6, 8, 12, and 16 hours after ingestion. The times to maximum [APAP] (Tmax); the maximum [APAP] values (Cmax); the elimination half-lives 4-16 hours postingestion (t1/2), and the areas under the [APAP] vs time curve (AUC) for ER APAP and IR APAP were compared using the paired t-test.

RESULTS

All the subjects completed both study phases. The mean APAP dose ingested was 5.6 g (range 4.2-7.8 g). Both the AUC and the Cmax were less after ER APAP than after IR APAP; otherwise, there was no evident difference in any measure. Graphically, ER APAP yielded a flatter, plateau-shaped curve initially, but after 4 hours the curve was nearly identical to that for IR APAP. Results are summarized in the table: [table: see text]

CONCLUSION

In this model involving a single supratherapeutic dose, ER APAP evidenced no pharmacokinetic features that would suggest the need for an alternate poisoning screening strategy. When compared with IR APAP, ER APAP had a lower AUC, all peak [APAP] occurred in < 4 hours, and terminal eliminations were identical. The data suggest that, in most cases, the diagnostic approach to an overdose of ER APAP need not deviate from that used for an IR APAP overdose.

Pediatric poisonings

In a general exposition of clinical and laboratory issues in the emergency management of poisoning in the pediatric patient I briefly discuss the epidemiology of poisonings in the child population, the categories of poisons to which children are exposed most frequently, and clinical and laboratory considerations, focusing on the importance of understanding the pharmacological properties of the compound involved. I review diagnostic and therapeutic decision-making in light of the characteristics of the known or suspected chemical involved. Finally, the information presented is integrated in a discussion of two cases of poisoned patients in a hospital emergency department.

Hospitalisation for deliberate self-poisoning in Scotland from 1981 to 1993: trends in rates and types of drugs used

BACKGROUND

Rates of self-poisoning fell during the 1980s, although recent reports suggest this trend may have reversed.

METHODS

Data on all hospital discharges with a diagnosis of deliberate self-poisoning were obtained from the Information and Statistics Division of the NHS in Scotland. Rates of self-poisoning were investigated by overall trend, and for trends by age and by type of drug.

RESULTS

Deliberate self-poisoning rates for men and women began increasing in the late 1980s, and did so steadily during the early 1990s. Because the rates are increasing faster in men, the traditional excess of self-poisoning among women is being eroded. For men rates increased in all age groups up to the age of 60, but the greatest rise occurred between ages 15-29. For women the increase was largely restricted to 15-24-year-olds, and rates fell among women over the age of 50. Self-poisoning with paracetamol increased most rapidly; in contrast to aspirin which showed little change. Opiate analgesics, antirheumatics, antidepressants and antipsychotics have also shown some increase in their use in both genders. There has been a substantial fall in the use of benzodiazepines in women, but little change among men.

CONCLUSION

Rapid increases in self-poisoning particularly among young adults present a serious public health problem. Controlling this epidemic is made difficult because the principal drug involved, paracetamol, is readily available.

Outpatient N-acetylcysteine treatment for acetaminophen poisoning: an ethical dilemma or a new financial mandate?

The mainstay of treatment for acetaminophen-induced hepatotoxicity, produced by the accumulation of the toxic metabolite N-acetylbenzoquinoneimine, is an enteral 18-dose course of N-acetylcysteine (NAC). However, absence of characteristic symptomatology is a frequent reason for premature cessation of NAC and early discharge of the toxic acetaminophen poisoned patient. We report a series of confirmed acetaminophen poisonings who were discharged early with NAC and instructions to self-administer. All cases of acute acetaminophen poisoning without concomitant drugs, reported to a certified Regional Poison Information Center for a 3-mo period of time, were reviewed. Inclusion criteria included patients who were discharged with orders to complete the course of NAC outside of a hospital, despite toxic serum acetaminophen concentrations. Data parameters evaluated included age, amount taken, symptoms, laboratory results, treatment, and medical outcome. 131 cases of confirmed toxic acetaminophen poisoning yielded 6 patients who received 4 to 6 doses of NAC during hospitalization, but were discharged to home with the remaining 11-13 doses. Patients' ages ranged from 16-28 y (mean 20.0 y). Serum acetaminophen concentrations measured at 4 h post-ingestion ranged from 171-198 mcg/ml (mean 182 mcg/ml). Follow-up by the certified Regional Poison Information Center at 1-3 w post-discharge determined dosing compliance to be 83%. All 6 patients remained asymptomatic with normal liver function testing. Since health care reform encourages practitioners to reconsider established approaches to the delivery of health care, perhaps home delivery of NAC would not only be clinically preferred to premature cessation of the antidote, but also offer cost savings. Self-administration of NAC in the home setting may be representative of a new era in America's health care delivery system.

Presentation of poisoned patients to accident and emergency departments in the north of England

1. A 12 week prospective survey of all patients of any age with confirmed or suspected poisoning presenting to six accident and emergency departments in the North East of England was performed to establish the local incidence and patterns of presentation of poisoning. 2. 945 episodes of poisoning involving 852 patients were recorded representing approximately 1.2% of all A&E presentations and suggesting an annual attendance rate of 2.7 per 1000 persons per year. 3. Attendance rates varied threefold between hospitals and were similar in males and females overall; between the ages of five and 14 attendances were more common in females (1.9 vs 0.6/10(3)/y) while between 0 and 4 y (3.1 vs 2.4) and 25 and 34 y (3.9 vs 2.9/10(3)/y) they were more common in males. 4. The median interval between poisoning and presentation was 2 h (mean 4.1 h) and only 19% of cases presented within 1 h. Presentation was most common between Friday evening and Tuesday morning and in the late afternoon and evening. 5. 6% of the patients presented more than once with poisoning during the study period and 37% had a past history of deliberate self-harm. The most common poisons involved were paracetamol (43%), opioids (15%) and benzodiazepines (15%). 6. The study illustrates the frequency of presentations of poisoning to A&E departments. The high rate of poisoning in young men and the increasing use of paracetamol are particular causes for concern.

Coagulation factor V levels as a prognostic indicator in fulminant hepatic failure

Data reported by Bernuau et al. have strongly supported the measurement of coagulation factor V as the best prognostic indicator in fulminant hepatic failure (FHF) and as the test on which selection for urgent liver transplantation should be made. In this study, we have measured plasma factor V in 110 patients with FHF, in grades I-IV coma, in 88 of whom the etiology was acetaminophen overdose. On admission, patients who did not survive had significantly lower factor V levels (median, 5%; range, 1-27; n = 49), compared with those who did (median, 10%; range, 2-70; P < .001). In the 81 patients with acetaminophen-induced FHF who did not receive a transplant, there was no cutoff level of factor V that clearly separated the patients. On statistical analysis, a positive predictive value (the mortality in patients predicted to have a poor prognosis) of 0.49 was calculated for factor V <20% and 0.57 for factor V < 10%. If the prognostic criteria included deep coma (grades III and IV) as well as factor V <20%, a positive predictive value of 0.73 was calculated. This compared with a value of 0.92 for the well-established King's prognostic criteria based on pH, and a combination of international normalized ratio (INR), renal failure, and coma. In the 17 mixed, nonacetaminophen group of patients who did not receive a liver graft, the positive predictive value was 0.85 for a factor V level <20% and 1.00 for factor V <10%, compared with 0.93 for the King's criteria for that etiologic group. This study demonstrates that the predictive accuracy of plasma factor V level is much less effective than the well-validated King's criteria in the selection of patients with acetaminophen-induced FHF needing liver grafting, although it may be useful in patients with FHF due to other causes.

Factors responsible for continuing morbidity after paracetamol poisoning in Chinese patients in Hong Kong

To determine those factors responsible for continuing prevalence of liver damage after paracetamol poisoning, 222 Chinese patients presenting to the Prince of Wales Hospital, Hong Kong from 1988 to 1993 were studied. Of the 27 patients with plasma paracetamol concentrations above the recommended "treatment line", 13 developed liver damage. Time elapsed between ingestion and treatment with intravenous N-acetylcysteine (NAC) was the most important prognostic factor. Failure to give NAC appropriately (50%) and late presentation (23%) were the main reasons for the continuing morbidity. Liver damage in some of the remaining patients (30%) could have been prevented if NAC was started in the Emergency Department within 8-15 hours of ingestion. Liver damage after paracetamol poisoning remains common (5.9%) in Hong Kong because of the failure to give NAC appropriately or late presentation. We hope to improve patient management by repeatedly emphasising the importance of adherence to the standard protocols and having the toxic plasma level results phoned directly to the duty registrars.