Non-medical use of loperamide in the UK and the USA

BACKGROUND

Loperamide is a mu-opioid receptor agonist that is available as an over-the-counter anti-motility agent in the US and UK; recommended maximum doses of 12-16 mg/day. Anecdotal reports of non-medical use (NMU) have increased over the past decade with supra-therapeutic doses (70-800 mg/day) associated with cardiotoxicity. Little data exists on the prevalence of loperamide NMU.

AIM

The aim of this study was to determine the prevalence of loperamide NMU in the UK and US and to describe characteristics of non-medical loperamide users.

DESIGN

The Researched, Abuse, Diversion and Addiction Related Surveillance (RADARS® ) Survey of Nonmedical Use of Prescription Drugs (NMURx) was utilized to study NMU of loperamide among the adult population in the UK and US in 2017. The RADARS® NMURx is anonymous and self-administered online.

METHODS

A total of 40,029 completed surveys were included (10,019 from the UK and 30,010 from the US). Respondents were asked questions about medical and NMU of loperamide, frequency of and reasons for NMU, route of use problematic drug use markers, and demographics.

RESULTS

Prevalence of lifetime loperamide use (95% CI) and lifetime NMU of loperamide were: UK 28.5% (27.67-29.4), and 0.66% (0.5-0.8), respectively; US 33.7% (33.1-34.2), and 5.19% (4.9-5.5), respectively. Problematic drug use markers were elevated in those who reported NMU of loperamide in both the UK and US, however high-risk use was more prevalent in the UK than in the US.

CONCLUSION

NMU of loperamide is common. In the current international environment of opioid addiction involving both therapeutic and illicit opioids, awareness of the NMU of loperamide is important.

The effect of an abuse-deterrent opioid formulation (OxyContin) on opioid abuse-related outcomes in the postmarketing setting

An extended‐release opioid analgesic (OxyContin, OC) was reformulated with abuse‐deterrent properties to deter abuse. This report examines changes in abuse through oral and nonoral routes, doctor‐shopping, and fatalities in 10 studies 3.5 years after reformulation. Changes in OC abuse from 1 year before to 3 years after OC reformulation were calculated, adjusted for prescription changes. Abuse of OC decreased 48% in national poison center surveillance systems, decreased 32% in a national drug treatment system, and decreased 27% among individuals prescribed OC in claims databases. Doctor‐shopping for OC decreased 50%. Overdose fatalities reported to the manufacturer decreased 65%. Abuse of other opioids without abuse‐deterrent properties decreased 2 years later than OC and with less magnitude, suggesting OC decreases were not due to broader opioid interventions. Consistent with the formulation, decreases were larger for nonoral than oral abuse. Abuse‐deterrent opioids may mitigate abuse and overdose risks among chronic pain patients.

A single-arm clinical trial of a 48-hour intravenous N-acetylcysteine protocol for treatment of acetaminophen poisoning

INTRODUCTION

Acetylcysteine prevents hepatic injury when administered soon after acetaminophen overdose. The most commonly used treatment protocols are a 72-hour oral and a 21-hour intravenous (IV) protocol. Between 1984 and 1994, 409 patients were enrolled in a study to describe the outcomes of patients who were treated using a 48-hour IV protocol. In 1991, an interim analysis reported the first 223 patients. The objective of this manuscript is to report the rates of hepatotoxicity and adverse events occurring during a 48-hour IV acetylcysteine protocol in the entire 409 patient cohort.

METHODS

This was a multicenter, single-arm, open-label clinical trial enrolling patients who presented with a toxic serum acetaminophen concentration within 24 h of acute acetaminophen ingestion. Patients were treated with 140 mg/kg loading dose followed by 70 mg/kg every 4 h for 12 doses. Serum aminotransferase activities were measured every 8 h during the protocol, and adverse events were recorded. The primary outcome was the percentage of subjects who developed hepatotoxicity defined as a peak serum aminotransferase greater than 1000 IU/L.

RESULTS

Four hundred and nine patients were enrolled, and 309 met inclusion for the outcome analysis. The overall percentage of patients developing hepatotoxicity was 18.1%, and 3.4% of patients treated within 10 h developed hepatotoxicity. One acetaminophen-related death occurred in a patient treated at 22 h. Adverse events occurred in 28.9% of enrolled subjects; the most common adverse events were nausea, vomiting, and flushing, and no events were rated as serious by the investigator.

CONCLUSIONS

Acetaminophen-overdosed patients treated with IV acetylcysteine administered as 140 mg/kg loading dose followed by 70 mg/kg every 4 h for 12 doses had a low rate of hepatotoxicity and few adverse events. This protocol delivers a higher dose of acetylcysteine which may be useful in selected cases involving very large overdoses.

The effects of paracetamol (acetaminophen) on hepatic tests in patients who chronically abuse alcohol - a randomized study

BACKGROUND

Retrospective accounts suggest that therapeutic doses of paracetamol can produce severe hepatic injury in patients with putative high-risk conditions, including alcoholism and infectious hepatitis. Metabolism of paracetamol to its hepatotoxic metabolite is enhanced in patients who abuse alcohol, who also have compromised liver defences from depressed hepatic glutathione.

AIM

To determine the effect of paracetamol on serum liver tests of newly abstinent subjects who abuse alcohol, including subjects with hepatitis C infection.

METHODS

A randomized, double-blind, placebo-controlled study. Adult alcohol abusers with a current drinking episode longer than 7 days received either placebo or paracetamol 4 g/day for 5 days.

RESULTS

Of 142 subjects enrolled, 74 received paracetamol and 68 received placebo. Mean ALT activity during treatment increased from 48 to 62 IU/L in the paracetamol group and from 47 to 49 IU/L in the placebo group. Maximum ALT was 238 and 249 IU/L in the paracetamol and control groups respectively. The INR remained unchanged and serum bilirubin decreased in both groups. Subgroup analyses for subjects with alcoholic hepatitis, hepatitis C virus antibody and other subgroups showed no statistical difference between groups.

CONCLUSION

Administration of paracetamol 4 g/day appears safe in newly abstinent patients who abuse alcohol.

A randomized trial to determine the change in alanine aminotransferase during 10 days of paracetamol (acetaminophen) administration in subjects who consume moderate amounts of alcohol

BACKGROUND

Previous studies have suggested that therapeutic doses of paracetamol (acetaminophen) are safe in alcoholic patients when administered for up to 3 days. However, 14 days of therapeutic doses of paracetamol has been associated with an increase in serum transaminases.

AIM

To determine the effect of 10 days of the maximal therapeutic dose of paracetamol on serum alanine aminotransferase (ALT) activity in subjects who consume 1 to 3 alcoholic beverages per day.

METHODS

This was a randomized, double blind, placebo-controlled trial. Subjects took 4 g of paracetamol (or placebo) daily for 10 days. Serum aspartate aminotransferase (AST), ALT, bilirubin and INR were measured at baseline, day 4 and day 11. Symptoms potentially related to liver injury were also recorded.

RESULTS

Paracetamol and placebo groups had no change from baseline values at day 4, but the paracetamol group had an increase in mean ALT at day 11 of 8.7 IU/L. No subject developed symptoms of liver injury or met predefined criteria for hepatotoxicity or liver failure.

CONCLUSION

Therapeutic dosing of paracetamol administered for 10 days appears to elevate serum ALT in moderate drinkers, but does not produce clinically evident liver injury.

The effect of acetaminophen (four grams a day for three consecutive days) on hepatic tests in alcoholic patients--a multicenter randomized study

BACKGROUND

Hepatic failure has been associated with reported therapeutic use of acetaminophen by alcoholic patients. The highest risk period for alcoholic patients is immediately after discontinuation of alcohol intake. This period exhibits the largest increase in CYP2E1 induction and lowest glutathione levels. Our hypothesis was that common liver tests would be unaffected by administration of the maximum recommended daily dosage of acetaminophen for 3 consecutive days to newly-abstinent alcoholic subjects.

METHODS

Adult alcoholic subjects entering two alcohol detoxification centers were enrolled in a prospective double-blind, randomized, placebo-controlled trial. Subjects were randomized to acetaminophen, 4 g/day, or placebo for 3 consecutive days. The study had 95% probability of detecting a 15 IU/L difference in serum ALT.

RESULTS

A total of 443 subjects were enrolled: 308 (258 completed) received acetaminophen and 135 subjects (114 completed) received placebo. Study groups did not differ in demographics, alcohol consumption, nutritional status or baseline laboratory assessments. The peak mean ALT activity was 57 +/- 45 IU/L and 55 +/- 48 IU/L in the acetaminophen and placebo groups, respectively. Subgroup analyses for subjects presenting with an elevated ALT, subjects fulfilling a diagnosis of alcoholic hepatitis and subjects attaining a peak ALT greater than 200 IU/L showed no statistical difference between the acetaminophen and control groups. The one participant developing an increased international normalized ratio was in the placebo group.

CONCLUSION

Alcoholic patients treated with the maximum recommended daily dose of acetaminophen for 3 consecutive days did not develop increases in serum transaminase or other measures of liver injury. Treatment of pain or fever for 3 days with acetaminophen appears safe in newly-abstinent alcoholic patients, such as those presenting for acute medical care.

Rethinking the Toxic Methanol Level

INTRODUCTION

Treatment thresholds for methanol poisoning are based on case reports and published opinion. Most guidelines recommend treatment for a methanol level > or = 20 mg/dL in a nonacidotic patient. No supportive data have been offered nor has the time of the exposure been addressed. For instance, no distinction has been drawn between a methanol level drawn 1 hr vs. 24 hr from ingestion. We analyzed all published cases of methanol poisoning to determine the applicability of the 20 mg/dL threshold in a nonacidotic patient, specifically those arriving early for care (within 6 hr) with a peak or near-peak blood methanol concentration.

METHODS

Using predefined search criteria, a systematic review of the world literature was performed using MEDLINE and EMBASE. In addition, each article's references were hand searched for pre-1966 articles, as were fatality abstracts from all U.S. poison centers. Human cases were included if they reported a known time of a single methanol exposure, acid-base data, blood methanol, and blood ethanol (if not acidotic).

RESULTS

Dating to 1879, 372 articles in 18 languages were abstracted using a standard format; 329 articles (2433 patients) involved methanol poisoning, and 70 articles (173 patients) met inclusion criteria. Only 22 of these patients presented for care within 6hr of ingestion with an early methanol level. All but 1 patient was treated with an inhibitor of alcohol dehydrogenase (ADH). A clear acidosis developed only with a methanol level > or = 126 mg/dL. The patient that did not receive an ADH inhibitor was an infant with an elevated early methanol level (46 mg/dL) that was given folate alone and never became acidotic. Intra and inter-rater reliability were 0.95.

CONCLUSIONS

Nearly all reports of methanol poisoning involve acidotic patients far removed from ingestion. The small amount of data regarding patients arriving early show that 126 mg/dL is the lowest early blood methanol level ever clearly associated with acidosis. Contrary to conventional teaching, there are case reports of acidosis after only a few hours of ingestion. The data are insufficient to apply 20 mg/dL as a treatment threshold in a nonacidotic patient arriving early for care. Prospective studies are necessary to determine if such patients may be managed without antidotal therapy or dialysis.

Tricyclic antidepressants directly depress human myocardial mechanical function independent of effects on the conduction system

OBJECTIVES

To measure the effect of tricyclic antidepressant drugs (TCAs) on human myocardial contractility.

METHODS

Human atrial tissue was obtained during cardiac bypass surgery. The tissue was harvested, suspended in a Tyrode buffer at 37 degrees C, and perfused with a 95%/5% oxygen-carbon dioxide mixture. Developed force was continuously measured using a force transducer and recorded by computer. After an equilibration period, escalating doses of amitriptyline or desipramine were added to the bath. All strips were exposed to the following five concentrations of each drug: 0 (control) 0.4, 4, 40, and 400 microM. The results for each experiment were expressed as the difference between the developed force measured prior to the addition of each concentration of drug and the developed force measured after a 30-minute exposure to the drug.

RESULTS

Desipramine decreased the developed force by 27%, 49%, and 74% at concentrations of 0.4, 40, and 400 microM, respectively. Amitriptyline decreased the developed force by 38% at the 40-microM concentration and by 89% at the 400-microM concentration. Untreated strips retained 94% of baseline developed force at 150 minutes.

CONCLUSIONS

Tricyclic antidepressants depress human myocardial function in a dose-dependent fashion independent of the effects on the cardiac conduction system. While previous work has demonstrated the effect of therapies for the reversal of impaired cardiac conduction following TCA poisoning, to the best of the authors' knowledge, no reports have documented the effects of therapy on direct myocardial depression. Additional therapies targeted at reversing the direct cardiodepressive effects of TCA may improve outcome following TCA poisoning.

Acetaminophen use in patients who drink alcohol: current study evidence

Package labeling for all over-the-counter pain relievers and fever reducers warns patients who drink 3 or more alcoholic beverages daily to consult with a physician before using these products. In the absence of accurate, consistent data, physicians have relied on retrospective and anecdotal evidence, which has perhaps led to greater restrictions on acetaminophen use than necessary for patients who consume alcohol. Recently, a well-controlled clinical study was conducted to more rigorously characterize the risk to alcohol users taking acetaminophen. In this randomized, double-blind, placebo-controlled trial, patients enrolled in a drug detoxification facility received 1000 mg acetaminophen or placebo 4 times daily for 2 consecutive days immediately after discontinuing alcohol use. Serum aspartate aminotransferase and alanine aminotransferase levels, used to detect hepatic necrosis or liver disease, were monitored at baseline and again both during and after the study. Results for 201 patients completing the study showed no statistically significant difference in liver function tests for 102 patients receiving acetaminophen compared with 99 patients receiving placebo. Researchers concluded that there was no increase in liver toxicity among alcoholic patients given the maximal therapeutic dose (4 g/day) of acetaminophen and no clinical evidence of increased risk for these patients when acetaminophen is used within recommended doses.

The use and effect of analgesics in patients who regularly drink alcohol

Analgesic consumption poses special risks for regular users of alcohol. Among the numerous adverse health effects are acetaminophen toxicity and gastrointestinal (GI) bleeding associated with nonsteroidal anti-inflammatory drug (NSAID) use. An alcohol-acetaminophen hypothesis contends that alcohol enhances acetaminophen toxicity. Because 22% of adults use acetaminophen each week and 5% to 10% of the population is alcoholic, the healthcare implications of serious adverse interactions are considerable. However, such interactions are rare when NSAID doses remain in the therapeutic range. Although clinical studies fail to support anecdotal case reports of liver damage associated with consumption of therapeutic doses of acetaminophen by alcohol users, such reports are probably inaccurate because of the uncritical acceptance of patient history by the clinician and a lack of well-designed prospective trials. Over-the-counter (OTC) NSAIDs, such as aspirin, naproxen, and ketoprofen, are other analgesic options, but each carries the risk of GI bleeding. Unanswered questions about the newer "second-generation" NSAIDs, such as celecoxib and rofecoxib, make them less desirable than acetaminophen and OTC NSAIDs. Because the risk of GI bleeding or ulceration may be higher in alcoholic patients, the optimal strategy in prescribing pain relievers to those who consume alcohol is to use 1 drug at a time and to clearly communicate its generic name. Acetaminophen is the safest OTC analgesic and is recommended as first-line treatment for osteoarthritis. OTC NSAID users should be carefully advised as to recommended dose, and all patients should be reminded to stay within the dosing limits regardless which OTC analgesic is used.

Effect of maximal daily doses of acetaminophen on the liver of alcoholic patients: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Retrospective reports suggest that therapeutic doses of acetaminophen may be associated with fulminant hepatic failure and death in alcoholic patients. Millions of patients use acetaminophen; the prevalence of alcoholism in the United States is 5% to 10%.

OBJECTIVE

To determine if hepatic injury was associated with maximal therapeutic dosing of acetaminophen to chronic alcohol abuse patients immediately following cessation of alcohol intake (the presumed time of maximal vulnerability).

METHODS

Patients entering an alcohol detoxification center were enrolled in a randomized, double-blind, placebo-controlled trial. Exclusion criteria were baseline values of aspartate or alanine aminotransferase greater than 120 U/L, international normalized ratio greater than 1.5, serum acetaminophen level greater than 20 mg/L, or a history of ingesting more than 4 g/d of acetaminophen. Acetaminophen, 1000 mg, or placebo was administered orally 4 times daily for 2 consecutive days and liver test results were monitored for 2 more days. Acetaminophen was not administered until the alcohol had been eliminated.

RESULTS

There were 102 patients in the acetaminophen-treated group and 99 patients in the placebo-treated (control) group. Demographic data, alcohol history, and baseline blood test results were similar in both groups. The mean (SD) aspartate aminotransferase level on day 4 was 38.0 +/- 26.7 U/L in the acetaminophen-treated group and 37.5 +/- 27.6 U/L in the placebo-treated group. There were 4 patients in the acetaminophen-treated group and 5 in the placebo-treated group who developed an increase in their serum aspartate aminotransferase level to greater than 120 U/L; it did not exceed 200 U/L in any patient. The mean (SD) international normalized ratio on day 4 was 0.96 +/- 0.09 in the acetaminophen-treated group and 0.98 +/- 0.11 in the placebo-treated group.

CONCLUSION

Repeated administration of the maximum recommended daily doses of acetaminophen to long-term alcoholic patients was not associated with evidence of liver injury.

Attenuation of verapamil-induced myocardial toxicity in an ex-vivo rat model using a verapamil-specific ovine immunoglobin

OBJECTIVE

To determine whether an ovine verapamil-specific immunoglobin G (V-IgG) attenuates verapamil toxicity in an ex-vivo rat left ventricular papillary muscle model.

METHODS

The authors dissected left ventricular papillary muscle strips from male Sprague-Dawley rats (350-410 g) and suspended them in an oxygen-perfused Tyrode buffer bath at 37.5 degrees C. Muscle strips equilibrated for 90 minutes under electrical stimulation of 1 Hz. Resting and developed tension (mg) were monitored continuously. A concentration-response trial was performed with verapamil concentrations ranging from 31 to 1,020 nM; 510 nM produced consistent reduction in developed tension. A trial of V-IgG was then conducted by administering the following treatments to papillary muscle strips in a randomized manner: V-IgG + 510 nM verapamil, nonspecific ovine IgG (N-IgG) + 510 nM verapamil (protein control), and 510 nM verapamil alone. Immunoglobin G was administered in equimolar concentrations to verapamil. Attenuation was expressed as inhibition of the verapamil-induced reduction of developed tension.

RESULTS

The V-IgG comparative trial indicated the V-IgG + verapamil treatment had a mean reduction in developed tension of 14.1% (SD +/- 12.2) compared with 36.2% (SD +/- 14.9) for N-IgG + verapamil and 34.9% (SD +/- 8.1) for verapamil alone (p < 0.05). There was no difference between the two control groups.

CONCLUSION

Verapamil-specific IgG attenuated verapamil-induced reduction of developed tension in an ex-vivo rat model.

Calcium neutralizes fluoride bioavailability in a lethal model of fluoride poisoning

OBJECTIVES

Acute systemic fluoride poisoning can result in systemic hypocalcemia, cardiac dysrhythmias, and cardiovascular collapse. Topical and intraarterial therapy with calcium or magnesium salts reduces dermal injury from fluoride burns. The mechanism of these therapies is to bind and inactivate the fluoride ion. The purpose of this study is to evaluate the effect of calcium and magnesium to decrease the bioavailability of fluoride in a lethal model of fluoride poisoning.

METHODS

In preliminary studies, we determined that fluoride 3.6 mM/kg intraperitoneally in the form of sodium fluoride was uniformly and rapidly fatal in a mouse model. Using this fluoride dose, we performed a controlled, randomized, blinded study of low- and high-dose calcium chloride (1.8 and 3.6 mM/kg intraperitoneally, respectively) and magnesium sulfate (3.6 mM/kg intraperitoneally) to decrease the bioavailability of the fluoride ion. After injection with sodium fluoride, animals were immediately treated with injections of sodium chloride (control), calcium chloride (low- or high-dose), or magnesium sulfate. The major outcome was 6-hour survival using a Cox Proportional Hazard model.

RESULTS

All untreated animals died within 60 minutes. Using a Cox Proportional Hazard model, each 1.8 mM/kg dose of calcium chloride administered reduced the risk of death by 33%. Magnesium sulfate treatment was not associated with a hazard reduction.

CONCLUSION

Calcium chloride administered simultaneously with sodium fluoride reduces the bioavailability of fluoride poisoning in a mouse model. The equivalent dose of magnesium sulfate does not significantly decrease fluoride bioavailability.

A randomized multicenter trial of crotalinae polyvalent immune Fab (ovine) antivenom for the treatment for crotaline snakebite in the United States

BACKGROUND

Current therapy for crotaline snakebite includes antivenin (Crotalidae) polyvalent, an antivenom with numerous adverse effects. We compared the efficacy and safety of 2 dosing regimens with a new antivenom, Crotalinae polyvalent immune Fab (Fab AV).

METHODS

A single dose of Fab AV alone (as-needed [PRN] group) was compared with an initial dose plus repeated treatments during 18 hours (scheduled group) in a multicenter randomized trial. The study included patients with minimal or moderate envenomation by a crotaline snake within the preceding 6 hours, aged 10 years or older, in whom worsening of the envenomation syndrome was observed before Fab AV treatment. After treatment with Fab AV to achieve initial control, patients were randomized to the scheduled or PRN treatment group. Scheduled group patients received additional doses of Fab AV every 6 hours for 3 doses. The PRN group received no planned additional doses of antivenom.

RESULTS

The mean severity score of the 31 patients decreased from 4.35 to 2.39 points (P<.001); there was no difference between scheduled and PRN groups. No patient in the scheduled group received unplanned Fab AV doses, but 8 of 16 patients in the PRN group received unplanned doses (P =.002). Acute reactions occurred in 6 patients (19%), and serum sickness occurred in 6 (23%) of 26 patients who returned for follow-up.

CONCLUSIONS

In the first randomized trial of antivenom in the United States, Fab AV effectively terminated venom effects. Since the unplanned use of Fab AV in the PRN group was common, the treatment regimen may require more than 1 initial dose.

Neutralization of Latrodectus mactans and L. hesperus venom by redback spider (L. hasseltii) antivenom

OBJECTIVE

To test the effectiveness of L. hasseltii (redback spider) antivenom in neutralizing the lethal effects of L. hesperus and L. mactans (North American black widow) venoms.

METHODS

LD50 values for the L. hesperus and L. mactans venom preparations were determined. A prospective, randomized, double-blind antivenom efficacy experiment was then performed for each venom using a mouse envenomation model. The following treatments were premixed and incubated at 25 degrees C for 1 hour prior to intraperitoneal injection: 1) saline control + protein control, 2) saline control + L. hasseltii antivenom, 3) L. hesperus or L. mactans venom + protein control, and 4) L. hesperus or L. mactans venom + L. hasseltii antivenom. The study endpoints were time elapsed until death and survival at 24 hours.

RESULTS

The mouse LD50 values for L. hesperus and L. mactans venoms were 0.64 mg/kg and 0.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both experiments, all mice in group 4 (L. hesperus or L. mactans venom + antivenom) survived (p < 0.0001).

CONCLUSION

This is the first study to derive mouse LD50 values for L. hesperus and L. mactans venom obtained by electrical stimulation of live adult spiders. Redback spider antivenom is effective in neutralizing the lethal effects of L. hesperus and L. mactans venoms in a mouse envenomation model. While this study is limited by the optimized premixing of antigen with antibody, it generates the hypothesis that redback antivenom would be effective in the treatment of latrodectism in humans caused by the two clinically relevant species of North American widow spiders.

Time to reconstitution: purified Fab antivenom vs. unpurified IgG antivenom

We conducted prospective, randomized analytical and observational trials to assess reconstitution times of two lyophilized crotaline snake antivenoms, Antivenin (Crotalidae) Polyvalent [Wyeth-Ayerst] (ACP) and affinity-purified, mixed monospecific crotalid antivenom ovine Fab (CroTAb) (Fab antivenom). The analytical experiment indicated Fab antivenom and ACP reached their maximum protein concentration at 25 and 45min, respectively. In the observational experiment, Fab antivenom (median 40min) had a shorter reconstitution time than ACP (>90min, p<0.008).

Acute myocardial infarction associated with amphetamine use

Myocardial infarction is a rarely reported complication of amphetamine use. We report the case of a healthy 31-year-old man who presented to our emergency department with no clinical evidence of an acute coronary event after intravenous injection of amphetamines. However, he subsequently experienced a non-Q-wave anterior wall myocardial infarction associated with the use of amphetamines.

Efficacy, safety, and use of snake antivenoms in the United States

The mainstay of hospital treatment for venomous snakebite is antivenom. There is currently only one antivenom available in the United States for the treatment of pit viper envenomation, Antivenin (Crotalidae) Polyvalent (ACP). The general indication for the administration of antivenom is presence of progressive venom injury. Progressive injury is defined as worsening local injury (eg, swelling, ecchymosis), a clinically important coagulation abnormality, or systemic effects (eg, hypotension, altered mental status). Unfortunately, there are no prospective data available regarding the efficacy of ACP. The efficacy of a new antivenom (CroFab; FabAV) composed of purified Fab specific to indigenous snake species has been demonstrated in prospective trials. FabAV appears as effective as IgG antivenoms. However, Fab molecules have a shorter half-life than IgG molecules and may allow recurrence of venom effects, if additional doses are not administered. It has also been found that other antivenoms, including ACP, also allow recurrence of venom effects. The Fab preparation has produced fewer acute or delayed (serum sickness) allergic reactions; however, further experience is needed to confirm this observation. Evaluation of this new antivenom has led to advances in our understanding of antivenoms in terms of solubility and durability. Fab fragments enter solution quickly, thereby shortening the time to antivenom administration and are remarkably stable under extreme conditions of heat and handling.

Occurrence of monomethylarsonous acid in urine of humans exposed to inorganic arsenic

Monomethylarsonous acid (MMA(III)) has been detected for the first time in the urine of some humans exposed to inorganic arsenic in their drinking water. Our experiments have dealt with subjects in Romania who have been exposed to 2.8, 29, 84, or 161 microg of As/L in their drinking water. In the latter two groups, MMA(III) was 11 and 7% of the urinary arsenic while the monomethylarsonic acid (MMA(V)) was 14 and 13%, respectively. Of our 58 subjects, 17% had MMA(III) in their urine. MMA(III) was not found in urine of any members of the group with the lowest level of As exposure. If the lowest-level As exposure group is excluded, 23% of our subjects had MMA(III) in their urine. Our results indicate that (a) future studies concerning urinary arsenic profiles of arsenic-exposed humans must determine MMA(III) concentrations, (b) previous studies of urinary profiles dealing with humans exposed to arsenic need to be re-examined and re-evaluated, and (c) since MMA(III) is more toxic than inorganic arsenite, a re-examination is needed of the two hypotheses which hold that methylation is a detoxication process for inorganic arsenite and that inorganic arsenite is the major cause of the toxicity and carcinogenicity of inorganic arsenic.

Recurrent coagulopathy after antivenom treatment of crotalid snakebite

BACKGROUND

We studied whether recurrence of coagulopathy, defined as the return of a coagulation abnormality after initial normalization, occurred after the use of antivenin (Crotalidae) polyvalent.

METHODS

A retrospective, blinded, descriptive analysis of 354 consecutive cases of North American crotalid snake envenomation was done. Inclusion criteria were documented clinical evidence of crotalid snakebite, presence of a coagulopathy (platelet count <150,000/mm3, prothrombin time above normal, or fibrinogen level <150 mg/dL), and treatment with antivenin (Crotalidae) polyvalent.

RESULTS

Of 112 cases with a coagulopathy extending beyond 6 hours after envenomation, 31 had sufficient coagulopathy testing to detect recurrence. Fourteen of these patients (45%) had recurrence of coagulopathy, and two cases were severe (fibrinogen level 29 mg/dL; platelet count 36,000/mm3).

CONCLUSION

Recurrence of coagulopathy after envenomation by North American crotalid snakes may occur after use of antivenin (Crotalidae) polyvalent and can result in severe coagulation abnormalities.

DMPS-arsenic challenge test. II. Modulation of arsenic species, including monomethylarsonous acid (MMA(III)), excreted in human urine

The administration of sodium 2,3-dimercapto-1-propane sulfonate (DMPS) to humans chronically exposed to inorganic arsenic in their drinking water resulted in the increased urinary excretion of arsenic, the appearance and identification of monomethylarsonous acid (MMA(III)) in their urine, and a large decrease in the concentration and percentage of urinary dimethylarsinic acid (DMA). This is the first time that MMA(III) has been detected in the urine. In vitro biochemical experiments were then designed and performed to understand the urinary appearance of MMA(III) and decrease of DMA. The DMPS-MMA(III) complex was not active as a substrate for the MMA(III) methyltransferase. The experimental results support the hypothesis that DMPS competes with endogenous ligands for MMA(III), forming a DMPS-MMA complex that is readily excreted in the urine and points out the need for studying the biochemical toxicology of MMA(III). It should be emphasized that MMA(III) was excreted in the urine only after DMPS administration. The results of these studies raise many questions about the potential central role of MMA(III) in the toxicity of inorganic arsenic and to the potential involvement of MMA(III) in the little-understood etiology of hyperkeratosis, hyperpigmentation, and cancer that can result from chronic inorganic arsenic exposure.

Treatment of pain or fever with paracetamol (acetaminophen) in the alcoholic patient: a systematic review

An unexpected clinical question has emerged in the treatment of pain or fever in the alcoholic patient: Is paracetamol a safe medication for the alcoholic patient? After decades of use in a variety of patients, sporadic reports suggest a relationship between liver injury and the use of paracetamol by alcoholic patients. We performed a systematic review of the medical literature to answer the question: Can administration of therapeutic doses of paracetamol cause hepatic injury in the alcoholic patient? After extensive data retrieval, each article in any language that involved the use of paracetamol by an alcoholic patient was abstracted and categorized for strength of evidence. Class I data (randomized, controlled trials) show that repeated ingestion of a therapeutic dose of paracetamol over 48 hours by patients with severe alcoholism did not produce an increase in hepatic aminotransferase enzyme levels nor any clinical manifestations compared with a placebo group. Class II data (prospective, nonrandomized trials) reveal that therapeutic doses of paracetamol have been administered to patients and an array of liver diseases (alcoholic, primary biliary, postnecrotic, or unspecified cirrhosis or alcoholic, acute viral, chronic active, or other infectious hepatitis) for periods up to 14 days without adverse effect. Finally, in several studies, a 1- to 2-g single dose of paracetamol was administered to alcoholic patients to study metabolism, again without adverse effect. In contrast, Class III data (retrospective case reviews and case reports) describe hepatic injury after repeated paracetamol ingestion with therapeutic intent, although usually not at therapeutic doses. Unfortunately, the information contained in Class III reports is often incomplete and contradictory. The history of ingestion is often unknown or contradicts other clinical information provided. For example, the history may indicate a therapeutic dose, but the serum paracetamol is elevated to levels only produced by ingestion much larger than the history indicates. In summary, all methodologically sound studies available indicate that therapeutic dosing of paracetamol to the alcoholic patient is not associated with hepatic injury. In fact, there is no change at all in hepatic aminotransferase enzymes, prothrombin time, or other biochemical parameters when compared with a placebo group in well-designed trials. Unless stronger evidence of a potentially dangerous interaction emerges, the use of paracetamol in the alcoholic patient is reasonable. During chronic treatment of pain, paracetamol may be preferred in the compliant alcoholic patients owing to the adverse effects associated with long-term use of nonsteroidal anti-inflammatory agents.

Treatment of amitriptyline poisoning with ovine antibody to tricyclic antidepressants

We report clinical improvement with the use of an ovine antibody (Fab fragment) to tricyclic antidepressants for the treatment of toxic effects of amitriptyline on the central nervous system and heart in a 48-year-old man.

Olanzapine overdose mimicking opioid intoxication

We report significant central nervous system depression and the previously unreported phenomenon of pupillary constriction after acute overdose of olanzapine (Zyprexa) in 4 patients. Phase 2 trials describe a typically benign course in overdose, and published abstracts note a wide spectrum of clinical effects with supratherapeutic ingestion of olanzapine. Our patients demonstrated profound central nervous system depression, and 2 required advanced airway support. All 4 patients recovered with supportive care. Olanzapine should be added to opioid and alpha(2)-adrenergic agonist intoxication in the differential diagnosis of the patient with depressed mental status and miosis.

Ingestion of low-concentration hydrofluoric acid: an insidious and potentially fatal poisoning

STUDY OBJECTIVE

The purpose of this study was to provide the first description of the effects of ingestion of low-concentration hydrofluoric acid in a population reported to a regional poison control center.

METHODS

A retrospective analysis of data collected by trained personnel using a standardized data collection system was performed. All charts involving hydrofluoric acid exposures for a 2-year period from a certified regional poison control center were identified by a computerized search. Each chart was abstracted by trained and blinded personnel.

RESULTS

There were 1,772 exposures to hydrofluoric acid; 135 involved ingestion. There were 99 cases of human hydrofluoric acid ingestion for analysis. All ingestions involved consumer products containing 6% to 8% hydrofluoric acid. Symptoms, most commonly mild gastrointestinal effects, were reported by 49 patients. Two patients with minimal effects during an observation period of 2 to 4 hours deteriorated suddenly and died. All other patients recovered completely. Of 29 cases in which calcium concentrations were recorded, 4 cases of hypocalcemia occurred. All patients who had major effects or died were adults who had ingested more than 3 ounces of hydrofluoric acid with suicidal intent. Death occurred precipitously in patients who had appeared well a few minutes earlier.

CONCLUSION

Death occurred in 2 patients, both of whom were adults who had ingested more than 3 ounces with suicidal intent. Ingestion of a household product containing hydrofluoric acid is a potentially life-threatening condition that requires close monitoring and prompt therapy. The abrupt deterioration and lack of warning signs indicate the need for better diagnostic methods.

Antivenom therapy in the Americas

Envenomations are an important cause of injury in the Americas. While supportive care alone may result in an acceptable outcome, antivenom offers a specific therapy that can significantly reduce the injury and symptoms of the envenomation. Antivenoms are hyperimmune sera collected from animals immunised with venom. The antibodies contained in the serum bind and inactive venom components. This leads to cessation or reversal of the toxic effects of the venom. The serum is often processed to increase the level of antibodies directed against venom components and decrease the amount of inactive proteins that may cause allergic reactions. The processing may include precipitation of inactive proteins, chromatographic methods and cleavage of the immunoglobulins to form antibody fragments known as Fab or F(ab)2. In the Americas, antivenoms are produced to treat crotalid and Micrurus snake envenomations. Latrodectus and Loxosceles spider envenomations and Centruroides and Tityus scorpion envenomations. The indications, method of administration and incidence of adverse reactions differ greatly for each antivenom. The adverse effects encountered when using antivenoms are primarily allergic in nature. Anaphylaxis, which may be life threatening, is a major concern. Preparations to treat anaphylaxis must be made before initiating antivenom therapy. Serum sickness is also common with many of the antivenom preparations.

Recurrent and persistent coagulopathy following pit viper envenomation

BACKGROUND

Coagulation abnormalities following crotaline (pit viper) snakebite have traditionally been considered short-lived, but laboratory studies have rarely been reported beyond the first few days of treatment for envenomation. During the course of an antivenom clinical trial, we observed coagulation defects as late as 2 weeks following envenomation.

OBJECTIVES

To document and characterize the recurrence or persistence of coagulopathy among patients envenomed by pit vipers and treated with a Fab antivenom.

METHODS

Patients with moderate pit viper envenomation were enrolled in a multicenter, prospective clinical trial. A Fab-based antivenom preparation, antivenom polyvalent crotalid (ovine) Fab, was administered in all cases. Platelet count, fibrinogen level, presence of fibrin split products, prothrombin time, and partial thromboplastin time were determined before treatment and at standard intervals during the following 2 weeks.

RESULTS

Of 38 patients completing the study, 20 (53%) had recurrent, persistent, or late coagulopathy 2 to 14 days after envenomation. Thrombocytopenia occurred in patients with prior thrombocytopenia; hypofibrinogenemia occurred only in those with prior hypofibrinogenemia or positive fibrin split products. No patient experienced significant spontaneous bleeding. One patient with coagulopathy developed minor bleeding following minor surgery 12 days after envenomation.

CONCLUSIONS

Prolonged or recurrent coagulopathy may occur after envenomation by North American pit vipers. Patients treated with Fab-based antivenom may benefit from periodic rather than single-bolus dosing. Patients with coagulopathy should undergo close monitoring during the first 2 weeks after snakebite.

Accidental, intravenous infusion of a peanut oil-based medication

OBJECTIVES

To describe a case of fat embolus syndrome with lipoid pneumonia resulting from intravenous infusion of lipid and to illustrate the potential for accidental intravenous administration of vegetable oil-based progesterone preparations in the treatment of oncology patients.

CASE REPORT

A patient with recurrent ovarian carcinoma accidentally received approximately 20 mL (0.29 mL/kg) of a peanut oil-based methylprogesterone product intravenously via infusion pump over 24 hours. The patient developed a lipoid pneumonia with dyspnea, cough, hypoxia, radiographic infiltrates, and a pleural effusion. She was hospitalized for 4 days, and signs and symptoms resolved over 2 weeks following steroids and supportive care.

DISCUSSION

Experience with accidental or intentional intravenous lipid overdose in humans is limited. Typical findings of fat embolus syndrome are similar to lipid aspiration, with respiratory distress, hypoxia, and pulmonary infiltrates. In contrast to aspiration, however, fat embolus syndrome results in lipogranulomas surrounding blood vessels, rather than air passages, and potentially produces cerebrovascular, accident-like symptoms. Management of fat embolus syndrome is similar to that for lipid aspiration. However, as seen in this case, fat embolus syndrome typically resolves over several weeks as opposed to the 3-month to 1-year period seen with aspiration lipoid pneumonias.

CONCLUSIONS

Accidental intravenous infusion of vegetable oil-based products is a potential complication of the increased use of intravenous progesterones.

DMPS (2,3-dimercaptopropane-1-sulfonate, dimaval) decreases the body burden of mercury in humans exposed to mercurous chloride

DMPS (2,3-dimercaptopropane-1-sulfonate, Na salt), when used as a challenge test for mercury in workers involved in the production of a calomel skin-bleaching lotion and in direct contact with mercurous chloride, elevated urine levels of mercury. A DMPS treatment regimen was devised and initiated. Three days after the challenge test, DMPS was administered p.o. (400 mg per day) for 8 days, followed by a no-treatment period of five days. A new cycle of DMPS treatment for 7 days was initiated and followed by 5 days without treatment. A third period of treatment was begun for 6 days, followed by a 5-day no-treatment period. The urinary mercury greatly increased during those periods when DMPS was administered (1754, 314, and 173 microgram/24 h for the periods 1, 2 and 3, compared with 106, 48 and 53 microgram/24 h on the corresponding no-treatment periods). One of the workers presented signs of drug intolerance and was discharged after receiving the first cycle of treatment. DMPS treatment was effective in lowering the body burden of mercury and in decreasing the urinary mercury concentration to normal levels.

An examination of serial urinalyses in patients with North American crotalid envenomation

STUDY OBJECTIVE

To examine the incidence of abnormal urinalyses after rattlesnake envenomations and its association with bite severity and antivenom administration.

METHODS

A retrospective review of data collected in a prospective manner for an experimental crotalid antivenom trial. Subjects were individuals with minimal to moderate North American crotalid envenomations. Incidence and characterization of abnormal urinalysis after crotalid envenomation is presented. Additionally, the relationship of abnormal urinalysis to bite severity is examined. A preliminary test of antivenom protein urinalysis interference was also conducted.

RESULTS

Forty-three percent of the urinalyses reported prior to antivenom treatment had abnormalities. Thirty-three of 41 subjects (80%) had an abnormal urinalysis, defined as the presence of cells, blood, glucose, or protein, at some time during the 2-week period following envenomation. All but 3 of these subjects had urinalyses which returned to normal by 2 weeks postenvenomation. Fifteen of 22 subjects (68%) with minimal envenomations had an abnormal urinalysis at some time following envenomation, while 18 of 19 subjects (95%) with moderate envenomations had abnormal urinalyses (p < 0.05). In addition, high concentrations of antivenom added to urine were found to produce a positive urine dipstick test for protein.

CONCLUSION

In our study of patients with minimal to moderate North American crotalid envenomations, there was a high incidence of abnormal urinalyses. The urine abnormalities tended to be more common with increased bite severity and more frequent during the first few hours following envenomation. Antivenom appearance in the urine could be responsible for some of our findings.

Heat and motion stability of polyvalent Crotalidae antivenin, ovine Fab

This study was conducted to test the hypothesis that a Fab-based crotalid antivenin (FabAV) in commercially packaged vials will remain effective under more extreme heat and motion conditions than would be expected in field settings. Vials containing FabAV were subjected to heat or motion. The effect of heat or motion on the ED50 of FabAV was determined using a mouse model of crotalid snake envenomation. The ED50 for the heat stability groups (expressed as a ratio of mg antivenin to mg venom) were as follows: 4 degrees C x 60 days (control) = 26.5, 70 degrees C x 60 days = 66.3, 70 degrees C x 30 days = 52.4, 50 degrees C x 60 days = 25.8, 50 degrees C x 30 days = 34.0. The ED50 for the two motion stability groups were similar: 4 degrees C x 60 days = 40.3 and 70 degrees C x 60 days = 48.3. These results indicate that FabAV is heat stable at 50 degrees C for 60 days, but had less potency when heated to 70 degrees C for 30 days. FabAV appears less potent after agitation, but remains effective in the mouse model. We conclude that FabAV can be safely stored for at least 60 days without refrigeration under most field conditions where snake envenomation may occur.

Intravenous administration of oral N-acetylcysteine

OBJECTIVE

To report the indications and adverse events associated with administration of the oral N-acetylcysteine preparation by the intravenous route.

DESIGN

Retrospective consecutive case series analysis of 226,720 Toxic Exposure Surveillance System data sheets from a certified regional poison center during the period January 1, 1992 through December 31, 1993.

SETTING

A regional poison center certified by the American Association of Poison Control Centers.

PATIENTS

Seventy-six patients treated with the oral N-acetylcysteine solution by the intravenous route.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We report the indications and adverse events associated with the intravenous administration of the oral N-acetylcysteine preparation. Four (4/76, 5.3%) patients developed adverse events attributable to N-acetylcysteine. None of these events involved hemodynamic, cardiovascular, or pulmonary effects. All reactions occurred during infusion of the initial N-acetylcysteine dose. There were three (3/76, 3.9%) deaths overall; however, they were not attributable to the intravenous administration of the oral N-acetylcysteine preparation.

CONCLUSIONS

Intravenous administration of the oral N-acetylcysteine preparation appears to have limited adverse effects and offers another mechanism of delivery of the potentially lifesaving N-acetylcysteine when oral administration is not possible.

Prevention of gastrointestinal iron absorption by chelation from an orally administered premixed deferoxamine/charcoal slurry

STUDY OBJECTIVE

To investigate the effect of an orally administered premixed slurry of deferoxamine mesylate (DFO) and activated charcoal (AC) on the gastrointestinal (GI) absorption of ferrous sulfate under physiologic conditions.

METHODS

This was a prospective, crossover, controlled human volunteer study. Participants were healthy adult subjects aged 25 to 38 years. Volunteers ingested either 5 mg/kg ferrous sulfate alone, 5 mg/kg ferrous sulfate added to 25 g of 20% (weight/ volume) AC, or 5 mg/kg ferrous sulfate added to a premixed slurry consisting of 8 g of DFO and 25 g of 20% (weight/volume) AC. The same group of volunteers was used in each limb of the study. Serum iron concentrations were measured at baseline and at 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, and 24 hours after ingestion for all subjects. Urinary iron was determined over the first 12 hours after ingestion for each limb. The maximum iron concentration (Cmax), the time to maximum iron concentration (Tmax), and the area under the curve (AUC) were compared for all three limbs.

RESULTS

The AUC (P = .042) and Cmax (P = .017) were significantly lower in all subjects in the DFO/AC limb compared with the two control limbs. There was no significant difference in the Tmax iron concentration (P = .77). In the ferrous sulfate control limb, female volunteers had a significantly higher mean Cmax (P = .008) and AUC (P = .014) than males. Iron was undetectable in all baseline and 12-hour urine collections.

CONCLUSION

In this model, a premixed 1:3 (weight/weight) DFO/ AC slurry reduced the GI absorption of ferrous sulfate in adult volunteers under physiologic conditions.

DMPS-arsenic challenge test. I: Increased urinary excretion of monomethylarsonic acid in humans given dimercaptopropane sulfonate

The purpose of the present study was to evaluate in a novel manner the arsenic exposure of humans living in two towns in Northeastern Chile. Residents of one town drink water containing 593 microg As/l. Those in the control town drink water containing 21 microg As/l. Our hypothesis was that the administration of the chelating agent, 2,3-dimercaptopropane-1-sulfonic acid, Na salt (DMPS, DIMAVAL) would increase the urinary excretion of arsenic, alter the urinary profile of arsenic species and thus result in a better indication of the body load of arsenic and a better biomarker for arsenic exposure. The method used to evaluate these subjects was to give them 300 mg DMPS by mouth, after an overnight fast, and collect urine at specified time periods. The urine samples were analyzed for inorganic arsenic, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and total arsenic by hydride generation and atomic absorption spectrophotometry. The results indicated that: 1) During the 2-hr period after DMPS administration, MMA represented 42%, inorganic As, 20 to 22% and DMA, 37 to 38% of the total urinary arsenic. The usual range of the MMA percentage in human urine has been 10 to 20%. The % MMA increased almost equally for both the arsenic-exposed and control subjects. 2) The exposed subjects had a greater urinary excretion of total arsenic, before and after DMPS administration, than the control subjects. 3) Although buccal cells were obtained only from a few subjects, the prevalence of mononucleated buccal cells, an indication of genotoxicity, was 5-fold greater for those who consumed drinking water with the higher arsenic content than among control subjects. Our conclusions are that 1) DMPS has a highly specific effect in humans on MMA metabolism and/or urinary excretion; 2) the human body stores substantial amounts of arsenic; and 3) the urinary arsenic concentration after DMPS administration may be more indicative of the body burden of arsenic because it was greater than that found before DMPS was given.

Affinity-purified, mixed monospecific crotalid antivenom ovine Fab for the treatment of crotalid venom poisoning

SUBJECT OBJECTIVE

To test the efficacy and safety of a new antivenom, affinity-purified, mixed monospecific crotalid antivenom ovine Fab, in human subjects with minimal or moderate crotalid envenomation.

METHODS

We conducted a prospective multicenter clinical trial of 11 patients 10 years or older with progressive manifestations after mild to moderate crotalid snakebite. After giving their consent, subjects received four to eight vials of study drug and were then repeatedly examined over 48 hours and at 7 and 14 days after discharge. Each patient's clinical condition was evaluated serially with the use of a validated severity score, as well as on the basis of the investigator's assessment.

RESULTS

In all 11 subjects to the antivenom was judged by the investigator to have had a beneficial response. The severity score for each patient remained the same or decreased over the first 4 hours. However, two subjects demonstrated worsened condition 12 to 15 hours after antivenom administration. In no subject did an allergic reaction develop.

CONCLUSION

In this patient group, affinity-purified, mixed monospecific crotalid antivenom ovine Fab was associated with a halt of progressive crotalid venom poisoning. Initial safety data are promising but must be addressed further in subsequent studies.

Relationship of venom effects to venom antigen and antivenom serum concentrations in a patient with Crotalus atrox envenomation treated with a Fab antivenom

STUDY OBJECTIVE

To describe the association among venom antigenemia, serum antivenom concentrations, and venom effects in a 53-year-old woman who was bitten by a Western Diamondback rattlesnake (Crotalus atrox).

METHODS

The patient was enrolled in a multicenter trial of an investigational Fab antivenom. Her clinical condition and coagulation parameters were monitored for 2 weeks after the bite.

RESULTS

After antivenom administration, the progression of the venom's effects was arrested. The antivenom reversed some local venom effects, caused venom antigens to disappear from the blood, and resolved the patient's profound thrombocytopenia (before antivenom, 12,000/mm3; 1 hour after antivenom, 227,000/mm3). Local venom effects recurred twice in the 24 hours after antivenom administration but were easily managed with additional Fab antivenom. Venom antigenemia was detected on days 5 and 8 after the initial treatment and was accompanied in one instance by the new onset of hypofibrinogenemia (119 mg/L) that resolved spontaneously and in both instances by renewed profound thrombocytopenia. Repeat Fab antivenom does no days 6 and 9 were followed by increases in platelet count (from 16,000 to 40,000/mm3 and from 11,000 to 20,000/mm3, respectively) and by the reduction or disappearance of venom antigenemia. The patient sustained no significant bleeding complications, and all laboratory values had returned to normal 2 weeks after the bite.

CONCLUSION

Initial control of local symptoms and coagulopathy was prompt after the administration of Fab antivenom. Repeat doses during the 24 to 36 hours after a bite may be necessary for local control. Recrudescence of coagulopathy was likely due in part to renewed venom antigenemia after clearance of Fab antivenom. The role of Fab antivenom in the treatment of recurrent coagulopathy requires further study.

Tylenol Extended Relief overdose

In this report we describe the toxicokinetics of the Tylenol Extended Relief (TER) preparation of acetaminophen in human overdose. We collected 41 cases of TER overdose from five regional poison centers. Patients who met the following criteria were studied: a single ingestion of TER alone; confirmed time of ingestion; at least four acetaminophen determinations; and normal concentrations of liver function enzymes. With the exception of standard decontamination measures, treatment with N-acetylcysteine (NAC) if any acetaminophen level was above the treatment line of the Rumack-Matthew nomogram, and additional acetaminophen determinations, no interventions were recommended. Our study group comprised 13 patients, 12 female and 1 male, with single overdoses of 10.4 to 65 g TER. The acetaminophen elimination half-life was 3.1 +/- .8 hours (mean +/- SD; range, 1.3 to 4.0 hours; n = 12). The elimination phase for patients 2, 3, 4, 6, 8, 9, 11, 13 was delayed until 8.0 +/- 2.8 hours (range, 5 to 14 hours) after ingestion. Patients 3, 8, and 11--who had initial acetaminophen levels below the "possible toxicity" line of the Rumack-Matthew nomogram--later had acetaminophen levels above this line. No patient demonstrated a late or second acetaminophen peak. We conclude that the elimination half-life of TER acetaminophen is similar to that reported in overdose of immediate-release acetaminophen overdose. In a subgroup of patients, drug absorption continued beyond the 2 to 4 hours previously reported in immediate-release acetaminophen overdose. On the basis of our data, the use of a single 4-hour acetaminophen determination may lead to failure to recognize patients with potentially toxic TER ingestion. Until more toxicokinetic data are available, a reasonable approach would be to obtain at least one additional acetaminophen determination at least 4 to 6 hours after the first, if the first is obtained 4 to 8 hours after ingestion. NAC treatment should be initiated if either level is above the nomogram line but not if both levels fall below the nomogram line.

Association of rattlesnake bite location with severity of clinical manifestations

STUDY OBJECTIVE

To examine an association between bite location in cases of North American crotalid envenomation and the severity of clinical manifestations.

METHODS

We conducted a retrospective review of prospectively collected data for an experimental trial of crotalid antivenom. Our subjects were otherwise healthy individuals with minimal to moderate North American crotalid envenomation. We compared the severity of envenomation for patients with digit bites distal to the proximal interphalangeal joint and bites more proximal using a previously developed and validated snakebite severity score.

RESULTS

Thirteen subjects were classified as having distal bites and 24 as having proximal bites. At baseline (before antivenom administration), the distal group had a mean severity score of 2.9 +/- 1.1, whereas the proximal group had a mean severity score of 5.0 +/- 2.2 (P = .0024). Patients in the proximal group tended to demonstrate a more rapid initial decline in severity score after receiving antivenom than did the distal group.

CONCLUSION

In minimal to moderate North America crotalid envenomation, patients who sustained bites on distal aspects the digits tended to experience less severe clinical manifestations of envenomation. It is possible that an isolated bite to the distal aspect of a finger is an early marker of minimal envenomation.

Placental transfer of N-acetylcysteine following human maternal acetaminophen toxicity

OBJECTIVE

To determine whether the antidote for acetaminophen poisoning, N-acetylcysteine, administered to pregnant women with acetaminophen toxicity, crosses the placenta and can be measured in the newborn circulation following delivery.

DESIGN

Over a 15-month period, four pregnant women with acetaminophen toxicity, who delivered their infants while receiving the antidote N-acetylcysteine, were studied. Maternal and cord blood from three viable infants, and cardiac blood sampled during an autopsy on the fourth, were analyzed for the presence of N-acetylcysteine using high-performance liquid chromatography. Maternal and cord blood aminotransferase activities, and autopsy findings on the nonviable infant were used to assess hepatic injury.

RESULTS

N-Acetylcysteine was detected in the cord blood of three viable infants and in cardiac blood of a fourth, sampled at the time of autopsy. The mean N-acetylcysteine concentration in cord blood was 9.4 micrograms/mL (+/-1.3). This is well within the range associated with therapeutic doses of N-acetylcysteine typically administered to adults with acetaminophen poisoning. No adverse sequelae developed in the three viable infants. The fourth infant, delivered at 22 weeks gestational age died 3 h after birth. All mothers recovered and none of the four infants had evidence of acetaminophen-related toxicity.

CONCLUSIONS

This is the first study documenting placental transfer of N-acetylcysteine in humans and provides impetus for research establishing a direct antidotal effect of N-acetylcysteine in the fetus.

Insufficient stocking of poisoning antidotes in hospital pharmacies

OBJECTIVE

To determine whether antidotes for poisoning and overdose are available in hospitals that provide emergency department care.

DESIGN

Written survey of hospital pharmacy directors, each of whom reported the amount currently in stock of 8 different antidotes: antivenin (Crotalidae) polyvalent, cyanide kit, deferoxamine mesylate, digoxin immune Fab, ethanol, naloxone hydrochloride, pralidoxime chloride, and pyridoxine hydrochloride.

PARTICIPANTS

Pharmacy directors of all hospitals with emergency departments in Colorado, Montana, and Nevada.

MAIN OUTCOME MEASURES

Proportions of hospitals with insufficient stocking of each antidote, defined as complete lack of the antidote or an amount inadequate to initiate treatment of 1 seriously poisoned 70-kg patient.

RESULTS

Questionnaires were mailed to 137 hospital pharmacy directors and 108 (79%) responded. Only 1 (0.9%) of the 108 hospitals stocked all 8 antidotes in adequate amounts. The rate of insufficient stocking for individual antidotes ranged from 2% (for naloxone) to 98% (for digoxin immune Fab). In a multiple regression analysis, smaller hospital size and lack of a formal review of antidote stocking were independent predictors of the number of antidotes stocked insufficiently.

CONCLUSIONS

Insufficient stocking of antidotes is a widespread problem in Colorado, Montana, and Nevada. Although these states are served by a certified regional poison center, potentially lifesaving antidotes are frequently not available when and where they might be needed to treat a single poisoned patient.