Intrarenal distribution of ampicillin in the normal and diseased human kidney

Factors Influencing Renal Distribution of Antibiotics a Key to Therapy of Pyelonephritis

Pyelonephritis is often considered a benign disease, yet in some studies as high as 35 percent of the cases progressed to severe renal disease. Treatment failures occur because of relapse of infection, emergence of secondary infecting organisms, re-infection and the development of antibiotic resistance. In addition, inadequate renal tissue concentrations of antibiotics account for a majority of treatment failures. The factors which influence diffusion of antibiotics into renal tissues are discussed. The importance of renal medullary tissue levels of antibiotics is emphasized, as well as the influence that protein binding, non-ionic diffusion and the state of hydration have on these levels. Distribution kinetics of sulfisoxazole, ampicillin, tetracyclines, cephalosporins, nalidixic acid, nitrofurantoin, gentamicin, carbenicillin indanyl sodium, sulfamethoxazole and trimethoprim as they relate to the treatment of pyelonephritis are also presented.

Drug interactions with urate excretion in man

The effects of pyrazinamide and ampicillin on the uricosuric response to probenecid and benzbromarone were studied in six normal subjects. The amount of uric acid was calculated for the 24 h volume of urine and the urate and creatinine clearances were determined for each of three urinary collection periods in order to calculate the percentage Curate/Ccreatinine. Ampicillin alone caused a significant uricosuria in the 0-2 h (p less than 0.025) and 8-24 h (p less than 0.025) periods. Benzbromarone caused a significant reduction in all the parameters. These observations suggest that high concentrations ampicillin compete with uric acid for reabsorption, but that its delayed uricosuric action can be ascribed to the binding of this dipeptide to a charge-mediated receptor site on the brush border membrane of proximal tubular cells. It would also appear that benzbromarone is secreted by the pyrazinamide-sensitive mechanism for urate secretion as it can cause a paradoxical retention of urate, but leaves the other probenecid-sensitive secretory transport process unoccupied as indicated by the fact that it does not change the kinetics of ampicillin.

Intrarenal concentration-time profile of ampicillin after administration of bacampicillin to patients before nephrectomy

Nineteen patients with renal cancer who were to undergo nephrectomy received a single oral dose of bacampicillin 800 mg at approximately three (N = 5), six (N = 7), or nine (N = 7) hours before nephrectomy. Serum samples were taken at 30, 60, and 90 minutes after administration and at nephrectomy. Urine was collected immediately before operation. Samples of medulla and cortex tissues were immediately and carefully dissected from a healthy part of the removed kidney and homogenized with a buffer solution. All concentrations were determined by bioassay. Bacampicillin was well absorbed, with a mean +/- SD serum concentration of 16.0 +/- 11.4 mg/L at one hour. The concentrations in renal tissues were higher than the serum levels taken at the same time, and the highest concentrations were found in the urine. the mean ampicillin elimination half-life was approximately the same in the cortex, medulla, and urine, (2.7, 2.3, and 2.4 hr, respectively) but it was shorter in the serum (1.4 hr). Bacampicillin 800 mg produced concentrations in the renal tissues that were higher and more sustained than in the serum and were well above the minimum inhibitory concentrations for common urinary pathogens even ten hours after the dose.

Scarring as a factor affecting the eradication of microorganisms from the kidney in pyelonephritis

The inability of antimicrobial agents to penetrate scarred renal tissue may explain some therapeutic failures. We examined the effect of scarring on antimicrobial therapy by using a unique animal model in which both kidneys were infected to the same degree but only one kidney was scarred. Scar formation could not explain the failure of ampicillin or nitrofurantoin to eradicate renal infection, but co-trimoxazole was less effective in the presence of tissue damage and scar formation than in their absence.

Intrarenal distribution of ampicillin in the healthy and the infected rat kidney: a comparison of methods

The ampicillin concentration in the cortex of the normal and the infected rat kidney was determined by means of three different methods: tissue homogenate analysis, renal lymph analysis, and autoradiography. Both tissue homogenate analysis and autoradiography revealed that the cortical ampicillin concentration was about five times as high as the serum concentration. Renal lymph analysis disclosed that the ampicillin concentration in this fluid amounted to about 93% of the serum concentration. The discrepancy between these results can be explained on the basis of the binding of ampicillin to cellular components in the cortex. The results of the study of ampicillin distribution in infected rat kidneys with the aid of tissue homogenate analysis and autoradiography indicate that the ampicillin concentration was lower in the affected than in the intact tissue. Renal lymph analysis showed that the ampicillin concentration in the lymph was not affected by the presence of the infection. Quantitative autoradiography demonstrated that the ampicillin concentration in the cortical foci of infection was of the same order of magnitude as the serum concentration. For this kind of study autoradiography together with lymph analysis are recommended.

Intrarenal concentrations of ampicillin in acute pyelonephritis

The intracortical, medullary, and papillary distribution of ampicillin was studied in normal and pyelonephritic rats. At 4 days after induction of pyelonephritis, the animals were given a single injection of 100 mg of ampicillin per kg or were treated for 1 week with two daily doses of 100 mg/kg. Major differences in the intrarenal distribution of ampicillin were noted between normal and pyelonephritic animals. At 2 hours after injection, the concentrations of ampicillin in all parts of the infected kidneys were significantly lower (P less than 0.05) than in normal kidneys. The area under the curve (micrograms.minute per milliliter) over a 4-h period after single injection was much lower in the medulla (6.3 +/- 0.9) and papilla (29.6 +/- 4.2) of infected kidneys than in the medulla (11.2 +/- 1.6) and papilla (44 +/- 10.1) of noninfected kidneys. Whereas the ratio of concentration in tissue to concentration in serum ranged to 11.1 in the papilla of normal animals, this ratio was reduced to 2.4 in the presence of pyelonephritis. The diminution of the concentration gradient was also striking in the urine, where there was a reduction of more than threefold in pyelonephritic animals. One week of therapy resulted in a noticeable reduction of the inflammatory process associated with a return to near-normal intrarenal distribution of ampicillin. In normal rats treated with multiple doses, there were decreases of the antibiotic concentrations in serum and kidneys and in the area under the curve for these tissues.

Drug administration in renal failure

Renal failure impairs urinary excretion of drugs and may also modify drug action by alternations in protein binding, distribution, biotransformation and, possibly, by retention of active metabolites. Dialysis adds another variable by altering the blood levels of those drugs soluble in plasma water and therefore available for diffusion or ultrafiltration. Renal insufficiency clearly modifies decisions about the choice and dose of a wide variety of drugs. Although data are accumulating at a rapid rate, available information about the use of drugs in patients with kidney disease is rather limited. The following is a summary of recent information on the use of a variety of drugs frequently utilized in patients with impaired renal function. The guidelines presented here are not absolute, but they are intended to be practical and reasonable, based on current information for adult patients of average size with kidney disease.

Ampicillin blood levels as related to graded oral schedules

Twenty children, while hospitalized with pneu monia, were treated by randomization with graded dosages of oral ampicillin; five each received 50, 100, 150, or 200 mg/kg daily in four equally divided doses for at least five days. The peak serum levels rose from a mean of 1 mcg/ml with 50 mg/kg per day to 4 to 7 mcg/ml with 200 mg/kg per day. Mild to moderate diarrhea, encountered in two of the five patients of each study group, was apparently unrelated to dose, and did not hinder absorption of the drug to a clinically significant degree.