Nephrotoxicity in combined cephalothin and gentamicin therapy

Thiazine, antibiotic, bilirubin adducts

1. Electron charge transfer interactions of some phenothiazine derivatives with aminoglycoside antibiotics, beta-lactams and penicillin-related antibiotics and bilirubin were investigated with alternating current titrations. 2. Neither the beta-lactams nor penicillin-related drugs interacted. 3. However, the aminoglycoside antibiotics formed complexes with the phenothiazines. 4. Tobramycin and gentamicin each formed 1:2 adducts with carbenicillin. 5. The phenothiazines interacted with bilirubin forming concentration-dependent micellar adducts which were exciplexes. This may explain the appearance of xanthomata in patients medicated with phenothiazines.

Cephalosporin-aminoglycoside synergistic nephrotoxicity: fact or fiction?

A review of synergistic nephrotoxicity associated with the concomitant administration of aminoglycoside and cephalosporin antibiotics is presented. A combination of these antibiotics is frequently administered in clinical practice as initial therapy in the treatment of gram-negative bacillary infection. The nephrotoxicity associated with cephalosporin/aminoglycoside administration in humans has been characterized as an acute tubular necrosis. Attempts to investigate this type of toxicity in animals using the rat as the model have revealed that the rat kidney is not affected by the aminoglycoside/cephalosporin combination in the same manner as the human kidney. The results from studies using the rat were not predictive of the nephrotoxicity encountered in humans, and cephalosporins actually appear to protect the rat from aminoglycoside-induced renal damage. The mechanism of the protective effect in rats and the toxic effects in man remain unknown. A species differentiation clearly exists between man and rats with respect to the nephrotoxic effects of aminoglycoside/cephalosporin combinations. The weight of present evidence indicates that, in man, an aminoglycoside/cephalosporin combination is synergistically nephrotoxic.

Empiric treatment of fever in acute leukaemia with tobramycin-cephalothin, and the escape clause provision of corticosteroids

29 episodes of suspected septicaemia in patients with acute leukemia were treated empirically with tobramycin 180--240 mg/day intravenously together with cephalothin 12 g/day. Patients without documented infection who did not respond to antibiotics and whose fever developed after a course of cytotoxic drugs, were given the provision of high dose corticosteroid therapy. Infection was documented microbiologically or clinically in 13/29 episodes. Septicaemia was proven in 7, and 6 had pneumonia. Neutropenia was present in 18/29 episodes. A satisfactory response to initial therapy was achieved in 7/13 with documented infection and in 9/16 without proven infection. The overall good response was 55%, 5/7 cases with septicaemia, but only 2/6 with pneumonia responded well. The 2 septicaemia patients who did not respond had Pseudomonas aeruginosa sepsis. In 16 episodes without documented infection 7 did not respond to initial therapy. To 4 of them, who were subject to recent cytotoxic drug administration, high dose corticosteroid therapy was given, and 3 of them responded well. Of the remaining 3 non-responders, one became afebrile after cytostatic and one after prednisolone treatment. Serum assays of tobramycin were done on the 1st and 5th day of therapy and no difference in concentration was observed on these 2 occasions. Five patients developed renal failure, but this was attributed to antibiotic therapy only in 1, who initially had an elevated serum creatinine. It is concluded, that in hospitals where pseudomonas is not a dominating pathogen, tobramycin--cephalothin may be a good combination to start empiric therapy with. In patients without proven infection, who have recently been subjected to cytotoxic therapy, and who do not respond to the initial course of antibiotics, a high dose of corticosteroids may be tried, provided the patient is monitored for the hazard of bacterial infection.

Effect of cephalothin on measurement of creatinine concentration

Cephalothin, an antibiotic implicated as nephrotoxic, falsely elevates the creatinine concentration as determined by the Jaffé reaction in vitro. We studied this effect in vivo and demonstrated variable degrees of interference in determinations of plasma and urinary creatinine concentrations by two automated methods. Clinicians should be aware of this phenomenon in patients receiving cephalothin, both when monitoring renal function and when assessing patient reliability in the collection of timed urine specimens.

Cephalothin plus an aminoglycoside is more nephrotoxic than methicillin plus an aminoglycoside

In a prospective, randomised, double-blind trial to determine if cephalothin plus an aminoglycoside is more nephrotoxic than methicillin plus an aminoglycoside, patients were assigned to one of four treatment groups: cephalothin and gentamicin (C.G.), cephalothin and tobramycin (C.T.), methicillin and gentamicin (M.G.), or methicillin and tobramycin (M.T.). The incidence of definite nephrotoxicity was: C.G., 7/23 (30.4%); C.T., 5/24 (20.8%); M.G., 2/20 (10%); and M.T., 1/23 (4.3%). There was no statistically significant difference in nephrotoxicity between the combined gentamicin groups (C.G. and M.G.) and the combined tobramycin groups (C.T. and M.T.). Definite nephrotoxicity developed in 12/47 (25.5%) of the combined cephalothin groups (C.G. and C.T.) and in only 3/43 (7%) of the combined methicilllin groups (M.G. and M.T.). The combination of cephalothin plus an aminoglycoside is therefore more nephrotoxic than the combination of methicillin plus an aminoglycoside.