Study Objectives. To characterize patient‐reported sulfonamide allergies, assess the influence of these allergies on drug prescribing practices, and determine the frequency and nature of adverse reactions in patients with sulfonamide allergies who receive potentially cross‐reactive drugs.
Design. Prospective observational study.
Setting. Tertiary care hospital.
Patients. Ninety‐four hospitalized adult patients with reported sulfonamide allergies.
Measurements and Main Results. Patients were followed during their hospital stay to document prescribing of and adverse reactions to sulfonamide antibiotics and sulfonamide nonantibiotics. Allergy characteristics and prescribing of sulfonamide‐containing drugs were analyzed with descriptive statistics. Trimethoprim‐sulfamethoxazole (TMP‐SMX) allergy was reported by 42 patients (45%), whereas 42 patients (45%) did not recall the drug to which they were allergic. Fifty‐nine patients (63%) reported the allergy's physical manifestation as rash, 13 (14%) anaphylaxis, and 2 (2)% Stevens‐Johnson's syndrome. Median time since last reported allergic reaction to a sulfonamide‐containing agent was 20 years. Forty patients (43%) had been taking a sulfonamide nonantibiotic as an outpatient for an average of 6.2 years; 24 (60%) of those patients took furosemide. Sixteen (40%) of the patients receiving sulfonamide nonantibiotics reported an allergy to TMP‐SMX. Nine patients (10%) with no past sulfonamide nonantibiotic use received a sulfonamide nonantibiotic as an inpatient, with furosemide most commonly prescribed. No adverse events were reported before admission or observed during the inpatient stay (range 2–23 days).
Conclusions. Inpatient and outpatient use of potentially cross‐reactive drugs was observed in 52% of patients, although numerous patients were unable to give an accurate allergy history. No adverse effects were reported or documented with outpatient or inpatient sulfonamide nonantibiotic use, even among patients with histories of life‐threatening reactions to sulfonamides.
Development of bleeding gastroesophageal varices is a serious consequence of portal hypertension secondary to cirrhosis. Nonselective beta-blockers have been used to reduce portal pressures and prevent primary and secondary bleeding episodes. However, up to two thirds of patients may not respond appropriately to these agents. Nonselective beta-blockers combined with vasodilatory drugs result in enhanced lowering of portal pressures by targeting several mechanisms involved in this process. Unfortunately, this practice is associated with increased adverse effects, such as hypotension, and minimal reductions in mortality. Carvedilol possesses both nonselective beta-antagonist and alpha1-receptor antagonist activity. Given its combined mechanism of action, carvedilol presents a potential option for lowering portal pressures. Its effects on lowering portal pressures and its role in therapy are undefined. Using MEDLINE (1966-2003) and International Pharmaceutical Abstracts (1970-2003), the English-language literature was searched to identify human studies assessing carvedilol's effects on lowering portal pressure. In general, carvedilol therapy was associated with mean reductions of 16-43% in portal pressure, assessed by the hepatic venous pressure gradient (HVPG) after single and multiple doses. Studies comparing carvedilol with propranolol revealed equal or enhanced efficacy in lowering HVPG. Large percentages of patients had significant HVPG reductions to levels that prevent variceal bleeding. Carvedilol also was associated with substantial symptomatic hypotension, especially in patients with ascites or Child-Pugh class B or C cirrhosis. Efficacy and adverse effects generally seem to be dose related. Carvedilol appears to be a potentially viable option for treating portal hypertension. Further multiple-dose trials comparing carvedilol with standard therapy are needed to assess the agent's long-term safety and effectiveness in preventing variceal bleeding.
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