Sympathomimetic amines

Recognizing Hospital Adverse Drug Reactions

Adverse drug reactions (ADRs) are a frequently overlooked complication of drug therapy. The categories of drugs most commonly implicated include anticoagulants, antimicrobials, cardiac agents, CNS agents, diagnostic agents, nonsteroidal antiinflammatory agents, and hormones. In addition to knowing what drug classes most commonly produce ADRs, the clinician should also recognize what drugs are most frequently associated with specific ADRs. Anaphylaxis is one of the most serious, and potentially life-threatening, ADRs. Treatment of an anaphylactic reaction involves correcting the physiologic effects of released chemical mediators and also inhibiting the release of additional mediators. The mainstay of therapy is aqueous epinephrine. Severe reactions may require administration of aminophylline, inotropic agents, antihistamines, corticosteroids, and intravenous fluids. The best treatment for any ADR is prevention. Pharmacists can actively participate in the monitoring of risk factors, especially the number of drugs in a regimen, potential drug interactions, and drug allergies, which may predispose patients to ADR development. Pharmacists can also assist in the detection of ADRs by monitoring alerting orders. Other potential activities for pharmacists include providing timely and accurate information about ADRs ; educating patients, physicians, and other health care professionals; and influencing prescribing patterns to minimize the trend towards polypharmacy.

Quantitative analysis of amphetamine in femoral blood from drug-poisoning deaths compared with venous blood from impaired drivers

Background: Amphetamine is a major drug of abuse worldwide. Here we compare the concentrations of this stimulant amine in femoral blood in drug fatalities with venous blood from impaired drivers. Method: Amphetamine was determined in blood by isotope-dilution GC–MS after liquid–liquid extraction. Results: Amphetamine was the only drug identified in 36 fatalities at mean (median) and highest concentrations of 2.0 mg/l (1.5 mg/l) and 14.0 mg/l. In multiple-drug deaths (n = 383), the concentrations were 0.94 mg/l (0.4 mg/l) and 13.3 mg/l. In impaired drivers with amphetamine as the only drug (n = 6138), the concentrations were 1.0 mg/l (0.8 mg/l) and 11.9 mg/l, compared with 0.78 mg/l (0.6 mg/l) and 22.3 mg/l in multidrug users (n = 8250). Conclusion: Fatal amphetamine poisonings cannot be identified on the basis of the concentration in blood alone, owing to the development of tolerance and the toxicity of co-ingested substances.

National academy of clinical biochemistry laboratory medicine practice guidelines: recommendations for the use of laboratory tests to support poisoned patients who present to the emergency department

BACKGROUND

Exposure to drugs and toxins is a major cause for patients' visits to the emergency department (ED).

METHODS

Recommendations for the use of clinical laboratory tests were prepared by an expert panel of analytical toxicologists and ED physicians specializing in clinical toxicology. These recommendations were posted on the world wide web and presented in open forum at several clinical chemistry and clinical toxicology meetings.

RESULTS

A menu of important stat serum and urine toxicology tests was prepared for clinical laboratories who provide clinical toxicology services. For drugs-of-abuse intoxication, most ED physicians do not rely on results of urine drug testing for emergent management decisions. This is in part because immunoassays, although rapid, have limitations in sensitivity and specificity and chromatographic assays, which are more definitive, are more labor-intensive. Ethyl alcohol is widely tested in the ED, and breath testing is a convenient procedure. Determinations made within the ED, however, require oversight by the clinical laboratory. Testing for toxic alcohols is needed, but rapid commercial assays are not available. The laboratory must provide stat assays for acetaminophen, salicylates, co-oximetry, cholinesterase, iron, and some therapeutic drugs, such as lithium and digoxin. Exposure to other heavy metals requires laboratory support for specimen collection but not for emergent testing.

CONCLUSIONS

Improvements are needed for immunoassays, particularly for amphetamines, benzodiazepines, opioids, and tricyclic antidepressants. Assays for new drugs of abuse must also be developed to meet changing abuse patterns. As no clinical laboratory can provide services to meet all needs, the National Academy of Clinical Biochemistry Committee recommends establishment of regional centers for specialized toxicology testing.

Inotropes--an overview

It is essential that nurses understand the drugs they are using, and the measurements they are monitoring. Inotropes are powerful drugs with immediate action. The aim of this article is to give an overview of the inotropes used commonly in intensive care environments, plus some of those currently undergoing investigation.

Drug level monitoring of antiasthmatic drugs

In general assays pertaining to drug level monitoring (DLM) of antiasthmatic agents (except theophylline), published during the period 1978-1983, used mostly high-performance liquid chromatographic (HPLC) methodology (approximately 45%) with mass spectrometric (MS) based assays in second place (approximately 30%) followed by immunochemical techniques (approximately 25%). Whenever nanogram or subnanogram antiasthmatic drug concentrations had to be measured such as for the adrenergic stimulants or for the prophylactic agents, then both HPLC-and MS-based methodologies were employed with about equal frequency. The trend in DLM for the phosphodiesterase inhibitor class (theophyllines) seemed to be shifting towards the HPLC methodologies. In part, this was justified by the need for improved selectivity. This criterion appears to have been better satisfied by HPLC, but for all practical purposes the immunochemical methods are and will probably continue to prevail in the clinical laboratory setting until HPLC procedures become truly automated. In the case of DLM of corticosteroids used for the asthmatic, the situation is in our opinion still unclear. This is caused by the presence of endogenous corticosteroids and metabolites, the levels of which in man are known to vary. The current immunochemical procedures offer a facile but less selective option. The future for selective routine corticosteroid assays may well be in HPLC or gas chromatography coupled with MS.

Pathophysiology of haemorrhagic shock

The immediate effect of sudden blood loss is the activation of a variety of homeostatic responses. These include increased sympathetic activity and increased release or production of renin, angiotensin, anti-diuretic hormone, aldosterone, adrenocorticotrophic hormone, beta-endorphins, glucocorticoids, glucagon, erythropoeitin, 2-3 diphosphoglycerate, prostaglandins and complement. This may be followed by the release of many substances, some initially appropriate locally, and some the products of damaged cells, which may go on to cause both local and systemic damage. These include lysosomal enzymes, kinins, histamines, serotonin, lactic acid, free oxygen radicals, neutrophil proteases, fibrinogen degradation products, endotoxins, myocardial depressant polypeptides, and passive transferable lethal factor. The early and late effects on the cardiovascular and respiratory systems, and on the blood, brain, kidneys, gut, liver, pancreas, and on overall metabolism and cellular function, are considered in turn. Although an enormous research effort has increased our understanding of the pathophysiology of haemorrhagic shock, no special measures have yet been shown to influence morbidity or mortality in man. Management still hinges on the early recognition and treatment of bleeding, on general supportive measures, and on safeguarding each link in the oxygen delivery chain.

An evaluation of thermodilution cardiac output measurement using the Swan-Ganz catheter

Errors in thermodilution cardiac output measurement were quantitated to determine the order of accuracy of routine measurements performed by unskilled personnel. In vitro and in vivo studies were undertaken to examine factors affecting the volume and temperature of the injectate, catheter thermistor and computer performance, effect of respiration, use of cold (0-4 degrees C) versus ambient temperature (20-25 degrees C) injectate, and the interpretation of measurements. Ambient temperature injectate incurred unacceptably large errors; cold injectate (injections were timed with respiration) produced variations in performance by equipment and personnel which accounted for only 2% of the variation between successive measurements. Real changes in cardiac output and inherent variability of the downslope of the thermal curve, necessitating an empirically based calculation, account for up to 10% variation between successive measurements. When cold injectate was used, and the average of three corrected measurements taken, thermodilution cardiac output measurements were within 10% of a simultaneous dye dilution measurement.