Acute renal effects of amphotericin B

Drug-induced nephropathies

Drug-induced renal disease is a common problem. Drugs cause several renal syndromes, such as prerenal azotemia, fluid and electrolyte abnormalities, acute tubular necrosis, acute interstitial nephritis, and chronic interstitial nephritis. Acute renal failure due to acute tubular necrosis is the most common syndrome and is most frequently caused by aminoglycoside antibiotics, radiographic contrast agents, and amphotericin B. Avoidance of these drugs in volume-depleted or hypotensive patients with preexisting renal disease or in those receiving multiple nephrotoxic drugs is the most effective way to reduce nephrotoxicity. Acute interstitial nephritis is an immune process that is most commonly caused by penicillins, diuretics, allopurinol, nonsteroidal anti-inflammatory drugs, cimetidine, and sulfonamides. Prompt recognition of the disease and cessation of the responsible drug are usually the only necessary therapy. Chronic interstitial nephritis is most often seen after prolonged use of several different types of analgesic agents, including aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs. These patients develop recurrent papillary necrosis and eventually chronic renal failure. They are also at risk of developing transitional cell carcinomas of the urinary collecting system. Some patients who are receiving cyclosporine also develop chronic renal failure due to interstitial fibrosis.

Amphotericin B and amphotericin B methylester: effect on brush border membrane permeability

In order to explain the nephrotoxicity of polyene antibiotics such as Amphotericin B (AM), an effect on the tubule membrane permeability has been postulated. However, studies on the action of AM have been complicated by the use of sodium deoxycholate (DOC), a membrane dissociating detergent as a solvent. Recently, a derivative, the methylester aspartate salt of Amphotericin B (AME) has been synthesized, which is highly water soluble in the absence of organic solvents. We have tested the action of AM, DOC, and AME on the sodium permeability of brush border (BBM) vesicles isolated from rat kidney cortex. It was found that both AM and AME increased the 22Na uptake as measured by a rapid filtration technique. However, a large fraction of the AM action was due to the effect of DOC on the BBM sodium permeability. We also investigated the time- and dose-dependent action of AME on 22Na and 3H-D-mannitol efflux from BBM vesicles. After 15 sec of exposure, efflux from 22Na-preloaded vesicles was unchanged in the presence of 1 microgram AME/mg protein compared to control vesicles. With 10, 50, and 100 micrograms AME/mg protein, the efflux increased 16, 25, and 35% respectively; 260 micrograms AME/mg protein did not elicit a further increment in the 22Na efflux. In the same membrane vesicles 3H-D-mannitol efflux did not change. After preincubation of the membranes for 60 min with different concentrations of AME, the 15 sec 22Na efflux increased 26% in the presence of 1 microgram/mg protein AME with no change in the 3H-D-mannitol efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Antifungal chemotherapy

When the decision to treat a fungal infection is made, there are several antifungal agents available for use. AmB remains the first-line drug in the treatment of most systemic fungal infections. Miconazole should be used to treat patients who cannot tolerate AmB or who are infected with AmB-resistant organisms. Ketoconazole has a distinct advantage in that it is a relatively nontoxic oral agent and may prove very effective in treating non-life-threatening chronic fungal infections. Clinical experience with miconazole and ketoconazole is too limited at present to recommend them as first-line therapeutic agents, except in a limited number of clinical situations. 5-FC should only be used in combination with AmB to treat yeast infections.