A 36-year-old man with known HIV infection comes to the emergency department because of a two week history of malaise and non-productive cough. He has not been compliant with his HIV medications. He denies any illicit drug abuse. He has never been hospitalized in the past.
His temperature is 38.9 C (102 F) , blood pressure is 122/70 mm Hg, and pulse is 112/min. His oxygen saturation is 90% on room air. His BMI is 23 kg/m². His sternocleidomastoid muscles are prominent bilaterally with each respiration. Cardiac examination reveals tachycardia without any murmurs. Scattered rhonchi are heard on lung auscultation. His abdominal examination is within normal limits.
Laboratory results are as follows:

Chest x-ray shows bilateral patchy interstitial infiltrates.
Intravenous fluids and high dose intravenous trimethoprim-sulfamethoxazole are started.
The patient should be specifically monitored for which of the following?

Question

A 36-year-old man with known HIV infection comes to the emergency department because of a two week history of malaise and non-productive cough. He has not been compliant with his HIV medications. He denies any illicit drug abuse. He has never been hospitalized in the past.
His temperature is 38.9 C (102 F) , blood pressure is 122/70 mm Hg, and pulse is 112/min. His oxygen saturation is 90% on room air. His BMI is 23 kg/m². His sternocleidomastoid muscles are prominent bilaterally with each respiration. Cardiac examination reveals tachycardia without any murmurs. Scattered rhonchi are heard on lung auscultation. His abdominal examination is within normal limits.
Laboratory results are as follows:

Chest x-ray shows bilateral patchy interstitial infiltrates.
Intravenous fluids and high dose intravenous trimethoprim-sulfamethoxazole are started.
The patient should be specifically monitored for which of the following?

Quizplus · Accepted Answer

11ec193a_96a8_9241_853d_07e58a46970c_MD0002_00 Trimethoprim-sulfamethoxazole (TMP-SMX) is associated with the development of many side effects (shown in the above table), but with a relatively low rate (6-8%) in non-HIV patients. Skin and gastrointestinal (i.e., nausea, vomiting) side effects are seen most commonly. Trimethoprim-sulfamethoxazole can interfere with folate metabolism and should not be given to pregnant women or patients with folate deficiency. Also, patients with G6PD deficiency may develop a hemolytic episode if given TMP-SMX. Side effects occur much more commonly in HIV patients, in as many as 25-50% of patients, and with more severe reactions. Cutaneous side effects are seen in up to 15% of HIV patients and include Stevens-Johnson syndrome, exfoliative dermatitis, and toxic epidermal necrolysis. Trimethoprim-sulfamethoxazole most commonly causes hyperkalemia in HIV patients, especially with high drug doses. Trimethoprim blocks sodium channels in the apical membrane of distal tubular epithelial cells and prevents sodium for potassium exchange. Other drugs which inhibit sodium channels and induce hyperkalemia include spironolactone, amiloride, triamterene, and pentamidine. (Choice A) Trimethoprim-sulfamethoxazole is rarely reported to be associated with non-anion gap metabolic acidosis due to renal tubular acidosis, but not anion gap metabolic acidosis. (Choice C) Hypoglycemia is a rare complication of TMP-SMX therapy. (Choice D) Hypophosphatemia is commonly due to protease inhibitors and non-nucleoside reverse transcriptase inhibitors, but not usually seen with TMP-SMX. (Choice E) Rhabdomyolysis is rarely caused by TMP-SMX in HIV patients, but is more commonly due to drug interactions between some statins and HIV protease inhibitors, muscle infections, or HIV myopathy. Educational objective: Trimethoprim-sulfamethoxazole (TMP-SMX) causes more serious side effects in HIV patients, particularly in hospitalized patients. Hyperkalemia is the most common side effect, especially when given in high doses. __________ References: Trimethoprim-sulfamethoxazole induces reversible hyperkalemia. (http://www.ncbi.nlm.nih.gov/pubmed/8328737) Hyperkalemia and high-dose trimethoprim/sulfamethoxazole. (http://www.ncbi.nlm.nih.gov/pubmed/7633023) Hyperkalemia in hospitalized patients treated with trimethoprim-sulfamethoxazole. (http://www.ncbi.nlm.nih.gov/pubmed/8554227)

A 36-Year-Old Man with Known HIV Infection Comes to the Emergency