Rebound following hemodialysis of cimetidine and its metabolites

Choosing the right chronic medication for hemodialysis patients. A short ABC for the dialysis nephrologist

BACKGROUND

Adapting drug treatments for patients on hemodialysis with multiple chronic pathologies is a complex affair. When prescribing a medication, the risk-benefit analysis usually focuses primarily on the indication of the drug class prescribed. However, the pharmacokinetics of the chosen drug should also be taken into account. The purpose of our review was to identify the drugs to be favored in each therapeutic class, according to their safety and pharmacokinetic profiles, for the most common chronic diseases in patients on chronic hemodialysis.

METHODS

We conducted a narrative review of the literature using Medline and Web of Science databases, targeting studies on the most commonly-prescribed drugs for non-communicable diseases in patients on chronic hemodialysis.

RESULTS

The search identified 1224 articles, 95 of which were further analyzed. The main classes of drugs included concern the cardiovascular system (anti-hypertensives, anti-arrhythmics, anti-thrombotics, hypocholesterolemics), the endocrine and metabolic pathways (anti-diabetics, gastric anti-secretory, anticoagulant, thyroid hormones, anti-gout) and psychiatric and neurological disorders (antidepressants, anxiolytics, antipsychotics and anti-epileptics).

CONCLUSION

We report on the most often prescribed drugs for chronic pathologies in patients on chronic hemodialysis. Most of them require adaptation, and in some cases one better alternative stands out among the drug class. More pharmacokinetic data are needed to define the pharmacokinetics in the various dialysis techniques.

Vancomycin redistribution: dosing recommendations following high-flux hemodialysis

Although increased vancomycin clearance has been reported with highly permeable hemodialysis membranes (such as polysulfone), failure to consider post-dialysis redistribution could lead to unnecessary dosage supplementation. In protocol 1, twelve hemodialysis patients admitted for vascular access thrombectomy received 15 mg/kg of vancomycin as surgical prophylaxis. Post-operatively, patients underwent high-flux hemodialysis (HFHD) for two hours using a Fresenius F-80 polysulfone dialyzer (QB = 417 +/- 49, QD = 800 ml/min). Vancomycin's intradialytic clearance increased 13-fold compared to the patient's endogenous clearance (120 +/- 59 vs. 9 +/- 8 ml/min, respectively) yet dialysate recovery indicated that only 17% of body stores were removed (179 +/- 70 mg). Although serum vancomycin levels decreased 33% during HFHD, vancomycin levels increased in all patients following dialysis and the post-rebound values reached 87% of the pre-dialysis concentration. In protocol 2, eight outpatients receiving maintenance HFHD with a F-80 dialyzer (Kt/V = 1.29 +/- 0.08) were given 20 mg/kg of vancomycin immediately following dialysis on Monday; pre- and post-levels were measured during the next three dialysis treatments. The predialysis serum vancomycin levels were > 7.5 micrograms/ml (9.7 +/- 1.0 micrograms/ml; range 8.0 to 11.0) in all patients the following Monday. Thus, vancomycin clearance is increased during HFHD, but redistribution post-HD minimizes changes in serum levels. We recommend a 20 mg/kg i.v. loading dose and subsequent doses of 15 mg/kg every seven days; to account for individual variability, weekly vancomycin levels should be drawn before dialysis.

Distribution characteristics of mitoxantrone in a patient undergoing hemodialysis

The pharmacokinetic profile of mitoxantrone in a patient undergoing hemodialysis is described. Significant characteristics of our patient included lymphoma with liver involvement, tumor lysis syndrome, renal and hepatic failure. Combination chemotherapy consisted of mitoxantrone, vincristine, and cyclophosphamide. Mitoxantrone plasma samples were obtained prior to dosing and at 0, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.5, 7.0, and 12 h after the intravenous infusion of a 17-mg dose over 20 min. Serum concentrations were determined by high-performance liquid chromatography. The serum concentration versus time curve was consistent with a three-compartment model. However, rebounds in serum drug concentrations were detected during the last portion of dialysis and after its completion. The gamma elimination half-life could not be determined due to the continued detection of rebounds in drug concentrations throughout the postdialysis sampling period. The alpha and beta distribution phases did not appear to be affected by hemodialysis. The peak mitoxantrone concentration fell within the reported range. Mitoxantrone does not appear to be eliminated by hemodialysis, and dose adjustments are not needed in patients undergoing this procedure.

Pharmacokinetics of ampicillin (2.0 grams) and sulbactam (1.0 gram) coadministered to subjects with normal and abnormal renal function and with end-stage renal disease on hemodialysis

The single-dose pharmacokinetics of intravenously administered ampicillin (2.0 g) and sulbactam (1.0 g) were studied in normal subjects and in patients with various degrees of creatinine clearance (CLCR). Six normal subjects (CLCR, greater than 60 ml/min), six patients with mild renal failure (CLCR, 31 to 60 ml/min), four patients with severe renal failure (CLCR, 7 to 30 ml/min), and four patients requiring maintenance hemodialysis (CLCR, less than 7 ml/min) were studied. The terminal half-lives for ampicillin and sulbactam more than doubled in patients with severe renal failure compared with subjects with normal renal function and mild renal insufficiency. CLCR significantly correlated with ampicillin (r = 0.88) and sulbactam (r = 0.54) total body clearance. Mean steady-state volume of distribution and nonrenal clearance for ampicillin and sulbactam were not affected by renal function. Hemodialysis approximately doubled the ampicillin and sulbactam total body clearance. Mean totals of 34.8 +/- 4.0% of the ampicillin dose and 44.7 +/- 3.2% of the sulbactam dose were removed during a 4-h hemodialysis treatment. A slight rebound in concentrations in serum after hemodialysis was observed for both drugs in all four subjects. In hemodialysis patients, the ampicillin half-life was 17.4 +/- 8.0 h and the sulbactam half-life was 13.4 +/- 7.4 h. The ampicillin and sulbactam half-lives were appreciably altered during the hemodialysis period (means of 2.2 and 2.3 h, respectively). The nearly parallel decrease in total body clearance, with volume of distribution and nonrenal clearance remaining relatively constant, suggests that the same ratio of ampicillin to sulbactam is appropriate regardless of renal function. An adjustment of the ampicillin (2.0 g) and sulbactam (1.0 g) dose to twice daily would be appropriate in patients with a CLCR between 7 and 30 ml/min. Doses should be given every 24 h for those undergoing maintenance hemodialysis. On hemodialysis days, doses should be given after hemodialysis.

Carbamazepine clearance in hemodialysis and hemoperfusion

A 47-year-old woman with endstage renal disease and dialysis-induced encephalopathy was being treated with carbamazepine for myoclonus. Her carbamazepine serum concentration appeared to be therapeutic at 5.1 micrograms/ml. She experienced a seizure while on hemodialysis/hemoperfusion that was possibly related to the removal of carbamazepine during dialysis. The elimination of carbamazepine on a dialysis day was compared with elimination on a nondialysis day. The half-life and apparent clearance were the same for each day, indicating that hemodialysis/hemoperfusion had little effect on the overall removal of carbamazepine from the body. The possible reasons for this lack of effect are discussed.

Time course of gentamicin serum concentration rebound following hemodialysis

The rebound in gentamicin serum concentration following hemodialysis was studied in six patients with chronic renal failure. The patients were not infected at the time of the study and received a single dose of gentamicin 2 mg/kg before hemodialysis. Serum samples were obtained immediately after dialysis and at 0.5, 1, 2, and 3 hours following hemodialysis. The average increases in gentamicin serum concentrations were 3.6 percent at 0.5 hour, 12.6 percent at 1 hour, and 6.6 percent at 2 hours. An average decline of 4.2 percent occurred at three hours. Only the increase seen at one hour was significantly different from the gentamicin serum concentration immediately following hemodialysis. This rebound was of small magnitude, though, and may not be clinically significant.