Gary M. Oderda

Clinical manifestations of toxicity in a series of 784 boric acid ingestions

A retrospective chart review was conducted at two regional poison centers to determine the clinical outcome of boric acid ingestions and to assess the relationship between serum boric acid levels and clinical presentation. A total of 784 cases were studied; all but 2 were acute ingestions. No patients developed severe manifestations of toxicity, and 88.3% were entirely asymptomatic. The most common symptoms were vomiting, abdominal pain, and diarrhea. Lethargy, headache, lightheadedness, and atypical rash were seen less frequently. Boric acid levels were obtained in 51 patients and ranged from 0 to 340 micrograms/mL. Blood levels were 70 micrograms/mL or more in 7 patients; 4 remained asymptomatic, whereas the other 3 had nausea or vomiting. Dialysis was performed in 4 of these 7 patients, only 1 of whom had symptoms (vomiting). On the basis of data from 9 patients, the mean half-life of boric acid was determined to be 13.4 hours (range, 4.0 to 27.8). Hemodialysis in 3 patients significantly shortened the half-life compared with pre- and postdialysis half-lives. Our results suggest that acute boric acid ingestions produce minimal or no toxicity and that aggressive treatment is not necessary in most patients.

Relative toxicity of cyclic antidepressants

To compare the relative central nervous system and cardiac toxicity of amoxapine, maprotiline, and trazodone with the older tricyclic antidepressants, a three-year (1981 through 1983) retrospective review was performed on 1,313 cases involving cyclic antidepressant exposures reported to the Maryland Poison Center. Seizures were more common in the amoxapine (24.5%) and maprotiline (12.2%) groups, compared with either the tricyclic antidepressants (3.0%) or trazodone (0%) (P less than .01). A higher incidence of seizures also was observed in desipramine ingestors (17.9%) compared with other tricyclic antidepressants. No significant differences in the incidence of central nervous system depression or cardiotoxicity was found between the groups. These findings support reports of an increased incidence of seizures in overdoses of amoxapine and maprotiline, but do not substantiate claims of less cardiotoxicity.

In vitro study of lithium carbonate adsorption by activated charcoal

The purpose of this study was to determine whether lithium carbonate (Li2CO3) is effectively adsorbed by activated charcoal (AC). Either 0 (control), 1.5, 3.0 or 9.0 grams of AC were added to Li2CO3 (300 mg) in distilled deionized water or simulated gastric fluid USP, filtered and and the filtrate analyzed for lithium by flame photometry. Adsorption of lithium was dependent on AC concentration and pH. In water, lithium was 14.7%, 26.5% and 40.4% adsorbed at AC:Li2CO3 ratios of 5:1, 10:1 and 30:1, respectively (p less than 0.05). In simulated gastric fluid, there was no significant adsorption at any of the AC concentrations studied. Since simulated gastric fluid more closely resembles in vivo conditions, the efficacy of AC in lithium carbonate overdoses is questionable but in vivo studies are needed to confirm these findings.

Poisoning in the Elderly: Epidemiological, Clinical and Management Considerations

SummaryPoisoning is a significant problem in the elderly. The majority of poisonings in older people are unintentional and may result from dementia and confusion, improper use of the product, improper storage or mistaken identities. Depression is also common in the elderly and suicide attempts are more likely to be successful in this age group. The elderly patient’s recuperative abilities may be inadequate as a result of numerous factors including impaired hepatic or renal function as well as chronic disease processes.General management of poisoning in the elderly parallels management of younger adults, but it is especially important to ascertain underlying medical conditions and concurrent medications. In most poisonings, activated charcoal and cathartic are sufficient. Haemodialysis or haemoperfusion may be required at lower plasma drug concentrations in elderly patients. While the specific indications for antidotes are the same for all age groups, dosage alterations and precautions may need to be considered in the elderly.Drugs most often implicated in poisonings in the elderly include psychotherapeutic drugs, cardiovascular drugs, analgesics and anti-inflammatory drugs, oral hypoglycaemics and theophylline.Cardiovascular and neurological toxicities occur with overdoses of neuroleptic drugs and, more frequently and severely, with cyclic antidepressants. Patients with pre-existing cardiovascular disease are at particular risk of worsening ischaemic heart disease and congestive heart failure. Benzodiazepines only appear to produce significant toxicity during long term administration or in combination with other CNS depressants.Digoxin can cause both chronic and acute intoxication, most seriously cardiac toxicity including severe ventricular arrhythmias, second or third degree heart block or severe refractory hyperkalaemia. Immune Fab antibody is indicated for the management of digoxin toxicity, although patients dependent on the inotropic effect of digoxin may develop heart failure after digoxin Fab antibody administration. Nitrates can cause toxicity including headache, vomiting, hypotension and tachycardia from excessive sublingual, transdermal or intravenous doses. Conduction disturbances and hypotension occur with overdoses of antihypertensive drugs; these effects are mild with angiotensin converting enzyme (ACE) inhibitors, occasionally severe with β- blockers and of significant concern with calcium channel antagonists.The elderly commonly use aspirin and other salicylates, are more likely to develop chronic intoxications to these agents, and are more susceptible to severe complications such as pulmonary oedema. Salicylate poisoning, recognition of which is often delayed, should be considered in elderly patients with neurological abnormalities or breathing difficulties, especially in the setting of acid-base abnormalities. The clinical effects of NSAID overdose are mild and usually involve the central nervous system and gastrointestinal tract.Elderly patients are also more likely to develop hypoglycaemia when taking sulphonylurea agents even with therapeutic doses. Seizures and arrhythmias occur at lower serum theophylline concentrations in the elderly.Poison prevention efforts aimed at unintentional exposures are primarily focused on preventing toxic exposures from occurring and minimising the consequences of injury should a toxic exposure occur. Several potential poison prevention strategies are outlined below.

Simulated acetaminophen overdose: Pharmacokinetics and effectiveness of activated charcoal

STUDY OBJECTIVEnTo determine the absorption rate of a supratherapeutic dose of acetaminophen elixir and compare the effect of activated charcoal (AC) given at different time intervals on preventing acetaminophen absorption.nnnDESIGNnRandomized, nonblinded, crossover controlled study.nnnSETTINGnA certified regional poison control center.nnnPARTICIPANTSnTen healthy, adult male volunteers from 21 to 39 years old.nnnINTERVENTIONSnEach subject received 5 g acetaminophen (elixir) on four occasions: a control phase plus 30 g of AC administered 15, 30, or 120 minutes after acetaminophen. Serum acetaminophen levels were obtained during the control phase only, and 24-hour urine collections were obtained during all four phases.nnnMEASUREMENTS AND MAIN RESULTSnThe highest serum acetaminophen levels were measured 1.4 +/- 0.52 hours after ingestion, and absorption was 97% complete by a mean of 2.05 hours. The administration of AC at 15, 30, and 120 minutes after acetaminophen reduced urinary recovery of acetaminophen and metabolites by 48%, 44%, and 33%, respectively.nnnCONCLUSIONnAC significantly reduces urinary recovery but not absorption of acetaminophen when administered two hours after acetaminophen elixir.

Lunar Cycle and Poison Center Calls

An analysis of calls to the Maryland Poison Center was performed to assess whether a relationship exists between the moon periods and poison exposure calls. A given period was defined as the day of the lunar event +/- 2 days. Thirteen lunar cycles in which 22,079 calls occurred were analyzed. A larger proportion of total calls to the center and unintentional poisoning calls occurred during the full moon period. A significantly larger number of unintentional poisonings occurred in the full moon period compared to suicide attempts and drug abuse which occurred most frequently during the new moon period. The lunar cycle had no effect on the distribution of victims age or sex or the location of treatment.

Adsorption of Oral Antidotes for Acetaminophen Poisoning (Methionine and N-Acetylcysteine) by Activated Charcoal

An in vitro experiment was performed to assess the degree of adsorption of oral antidotes for acetaminophen poisoning, methionine and N-acetylcysteine, by activated charcoal. Results indicate that activated charcoal effectively adsorbs both methionine and N-acetylcysteine. Since these agents must be absorbed from the GI tract to prevent acetaminophen hepatotoxicity, concurrent administration of methionine or N-acetylcysteine and activated charcoal would be expected to markedly diminish their antidotal effectiveness.

Three fatal sodium azide poisonings.

SummaryWe report 3 cases and review the published literature on sodium azide ingestion. A 38-year-old man intentionally ingested 2 tablespoonsful of sodium azide in water and developed seizures, coma, hypotension and fatal ventricular arrhythmias within 2 hours. A 33-year-old male ingested an unknown quantity of sodium azide. In the emergency department he was unconscious and underwent immediate intubation and gastric lavage. Nitrite therapy was instituted without improvement. He remained acidotic despite bicarbonate therapy and developed hypotension which was unresponsive to pressor agents. He died approximately 8 hours after admission despite resuscitative efforts. A 52-year-old male ingested 1.5 to 2g of sodium azide and survived for 40 hours. Nitrite therapy was ineffective.The role of sodium nitrite in treating sodium azide toxicity by producing met haemoglobin which complexes with azide is discussed.

Central Nervous System Depression from Ingestion of Nonprescription Eyedrops

Tetrahydrozoline, an alpha adrenergic agent with vasoconstrictor and decongestant properties, is widely available without a prescription for symptomatic relief of “pink eye” and is found in such popular products as Murine Plus,@ Optigene III,@ Visine,@ and Visine AC@ in a 0.05% concentration. When used appropriately as an ocular decongestant, tetrahydrozoline is a safe drug without serious side effects. When it is taken orally, however, relatively small amounts can produce profound central nervous system (CNS) depression.iA Scattered reports describing toxicity due to tetrahydrozolinelA generally involve either the 0.1% nasal solution used as prescribed, or accidental oral ingestion of nasal solution. This report describes two cases of profound CNS depression associated with the accidental oral ingestion of tetrahydrozoline ophthalmic solution. To our knowledge, only one other case of toxicity with the 0.05% ophthalmic preparation has been reported.’ A retrospective review of 64 tetrahydrozoline exposures is discussed.

Ipecac use in the elderly: The unanswered question

An elderly patient experienced an intracerebral bleed temporally related to the administration of syrup of ipecac. The experience of the certified regional poison centers of the American Association of Poison Control Centers shows that this is an uncommon event. The use and safety of ipecac in the elderly has not been adequately addressed in the past.