Intravenous Vancomycin Pharmacokinetics in Automated Peritoneal Dialysis Patients

The pharmacokinetics of intravenous (IV) vancomycin was studied in automated peritoneal dialysis (APD) patients who received a single IV dose of vancomycin (15 mg/kg total body weight). Dialysate samples were collected at the beginning, middle, and end of dwells 1 – 3 (on-cycler), and at the end of dwells 4 and 5 (off-cycler), for a 24-hour period. Blood samples were collected at the beginning, middle, and end of dwells 1 – 3 (on-cycler), and at the end of dwell 5 (off-cycler) for a 24-hr period. Pharmacokinetics parameters were calculated assuming a one-compartment model. Glomerular filtration rate (GFR) and vancomycin clearance (Cl) values were normalized to 1.73 m2. Ten patients [4 males, 6 females; 47.4 ± 9.9 years of age (mean ± SD)] who had received PD for a median 3.5 months (range 2 – 66 months) were studied. Dwell times were 2.3 ± 0.1 hours on cycler and 7.3 ± 0.1 hours off cycler. Vancomycin half-life was significantly different on-cycler than off-cycler (11.6 ± 5.2 hr vs 62.8 ± 33.0 hr; p < 0.001). Vancomycin total Cl (ClT) was 7.4 ± 2.0 mL/min. Renal Cl (ClR) and PD Cl (ClPD) accounted for 23.6% and 28.0% of ClT, respectively. ClR correlated with GFR (ClR = 0.90 GFR – 1.01; r2 = 0.79; p = 0.008). Mean vancomycin serum and dialysate end-of-dwell concentrations were above minimum inhibitory concentration of susceptible organisms (5 mg/mL) for the first cycler and the second ambulatory exchanges only.

The results of this study suggest that, to provide adequate concentrations for susceptible organisms over a 24-hour period, current intermittent vancomycin dosing recommendations for PD-related peritonitis need to be changed to 35 mg/kg intraperitoneally on day 1, then 15 mg/kg IP thereafter ( i.e., once daily) in APD patients.

Intermittent Intravenous Piperacillin Pharmacokinetics in Automated Peritoneal Dialysis Patients

Background

Use of intermittent antibiotic dosing is increasing in the treatment of peritoneal dialysis (PD)-related peritonitis. We studied the pharmacokinetics of intravenous (IV) piperacillin in automated PD patients.

Patients and Methods

Eight patients (3 males, 5 females) were recruited and received a single IV dose of piperacillin (35 mg/kg actual body weight). Blood and dialysate samples were collected at the beginning, middle, and end of dwells 1 – 3 (on cycler), and end of dwells 4 – 5 (off cycler) for a 24-hour period. Baseline and 24-hour urine samples (nonanuric patients, n = 7) were collected. Pharmacokinetic parameters were calculated assuming a one-compartment model. Glomerular filtration rate (GFR) and piperacillin clearance (CL) values were normalized to 1.73 m2.

Results

The patients were 49.5 ± 10.1 years of age (mean ± SD) and had been receiving PD for a median of 3 months (range 2 – 66 months). Dwell times were 2.25 ± 0.06 hours on cycler and 7.26 ± 0.14 hours off cycler. Piperacillin half-life was not statistically different on or off the cycler (on cycler 1.99 ± 0.39 hr, off cycler 4.39 ± 5.4 hr; p = 0.12) and remained insignificant, even accounting for an outlier (on cycler 2.01 ± 0.41 hr, off cycler 2.54 ± 1.48 hr; p = 0.19). Piperacillin total CL (CLT) was 31.29 ± 6.02 mL/minute. Renal CL (CLR) and PD CL (CLPD) accounted for 8.8% and 16.8% of CLT; CLR correlated well with GFR (CLR = 0.86 GFR + 0.1; p < 0.000 03). Mean piperacillin serum and dialysate end-of-dwell concentrations were above minimum inhibitory concentration of susceptible organisms (8 μg/mL) for the three cycler exchanges only. Serum and dialysate concentrations predicted using a one-compartment model suggest that IV piperacillin 4000 mg would provide adequate concentrations for susceptible organisms over a 12-hour period.

Conclusion

The current IV piperacillin dosing recommendations of 4000 mg every 12 hours for PD-related peritonitis are appropriate for patients on automated PD. Intermittent intraperitoneal piperacillin is not recommended.

Acute hemolysis with acute renal failure in a patient with valproic acid poisoning treated with charcoal hemoperfusion

Hemoperfusion consists of the passage of anticoagulated blood through a column containing adsorbent particles. It was introduced in 1940 and refined from 1950 to 1970, and then introduced clinically for the treatment of acute intoxications between 1970 and 1980. Life-threatening valproic acid toxicity is an indication for coated charcoal hemoperfusion usually accomplished without complications, but we report a case of acute severe intravascular hemolysis during the time of hemoperfusion with coated charcoal column.

Intravenous vancomycin pharmacokinetics in automated peritoneal dialysis patients

The pharmacokinetics of intravenous (i.v.) vancomycin was studied in automated peritoneal dialysis (APD) patients who received a single i.v. dose of vancomycin (15 mg/kg total body weight). Dialysate samples were collected at the beginning, middle, and end of dwells 1-3 (on-cycler), and at the end of dwells 4 and 5 (off-cycler), for a 24-hour period. Blood samples were collected at the beginning, middle, and end of dwells 1-3 (on-cycler), and at the end of dwell 5 (off-cycler) for a 24-hr period. Pharmacokinetics parameters were calculated assuming a one-compartment model. Glomerular filtration rate (GFR) and vancomycin clearance (CI) values were normalized to 1.73 m2. Ten patients [4 males, 6 females; 47.4 +/- 9.9 years of age (mean +/- SD)] who had received PD for a median 3.5 months (range 2-66 months) were studied. Dwell times were 2.3 +/- 0.1 hours on cycler and 7.3 +/- 0.1 hours off cycler. Vancomycin half-life was significantly different on-cycler than off-cycler (11.6 +/- 5.2 hr vs 62.8 +/- 33.0 hr; p < 0.001). Vancomycin total CI (CI(T)) was 7.4 +/- 2.0 mL/min. Renal CI (CI(R)) and PD CI (CI(PD)) accounted for 23.6% and 28.0% of CI(T). respectively. CI(R) correlated with GFR (CI(R) = 0.90 GFR - 1.01; r2 = 0.79; p = 0.008). Mean vancomycin serum and dialysate end-of-dwell concentrations were above minimum inhibitory concentration of susceptible organisms (5 micro/mL) for the first cycler and the second ambulatory exchanges only. The results of this study suggest that, to provide adequate concentrations for susceptible organisms over a 24-hour period, current intermittent vancomycin dosing recommendations for PD-related peritonitis need to be changed to 35 mg/kg intraperitoneally on day 1, then 15 mg/kg i.p. thereafter (i.e., once daily) in APD patients.

Intermittent intravenous piperacillin pharmacokinetics in automated peritoneal dialysis patients

BACKGROUND

Use of intermittent antibiotic dosing is increasing in the treatment of peritoneal dialysis (PD)-related peritonitis. We studied the pharmacokinetics of intravenous (i.v.) piperacillin in automated PD patients.

PATIENTS AND METHODS

Eight patients (3 males, 5 females) were recruited and received a single i.v. dose of piperacillin (35 mg/kg actual body weight). Blood and dialysate samples were collected at the beginning, middle, and end of dwells 1-3 (on cycler), and end of dwells 4-5 (off cycler) for a 24-hour period. Baseline and 24-hour urine samples (nonanuric patients, n = 7) were collected. Pharmacokinetic parameters were calculated assuming a one-compartment model. Glomerular filtration rate (GFR) and piperacillin clearance (CL) values were normalized to 1.73 m2.

RESULTS

The patients were 49.5 +/- 10.1 years of age (mean +/- SD) and had been receiving PD for a median of 3 months (range 2-66 months). Dwell times were 2.25 +/- 0.06 hours on cycler and 7.26 +/- 0.14 hours off cycler. Piperacillin half-life was not statistically different on or off the cycler (on cycler 1.99 +/- 0.39 hr, off cycler 4.39 +/- 5.4 hr; p = 0.12) and remained insignificant, even accounting for an outlier (on cycler 2.01 +/- 0.41 hr, off cycler 2.54 +/- 1.48 hr; p = 0.19). Piperacillin total CL (CL(T)) was 31.29 +/- 6.02 mL/minute. Renal CL (CL(R)) and PD CL (CL(PD)) accounted for 8.8% and 16.8% of CL(T); CL(R) correlated well with GFR (CL(R) = 0.86 GFR + 0.1; p < 0.00003). Mean piperacillin serum and dialysate end-of-dwell concentrations were above minimum inhibitory concentration of susceptible organisms (8 microg/mL) for the three cycler exchanges only. Serum and dialysate concentrations predicted using a one-compartment model suggest that i.v. piperacillin 4000 mg would provide adequate concentrations for susceptible organisms over a 12-hour period.

CONCLUSION

The current i.v. piperacillin dosing recommendations of 4000 mg every 12 hours for PD-related peritonitis are appropriate for patients on automated PD. Intermittent intraperitoneal piperacillin is not recommended.

Pharmacokinetics of intermittent intravenous cefazolin and tobramycin in patients treated with automated peritoneal dialysis

There is increasing use of intermittent dosing of antibiotics to treat peritoneal dialysis (PD)-related peritonitis. The disposition of intravenous cefazolin and tobramycin was studied in automated PD (APD) patients. Ten patients were recruited and received a single intravenous dose of cefazolin (15 mg/kg) and tobramycin (0.6 mg/kg). Blood and dialysate samples were collected at the beginning, middle, and end of dwells 1 to 3 (on cycler), and at the end of dwells 4 to 5 (off cycler) for a 24-h period. Baseline and 24-h urine samples were collected. Pharmacokinetic parameters were calculated using a monoexponential model. Cefazolin and tobramycin half-lives were markedly different on cycler than off cycler (cefazolin on cycler : 10.67 +/- 4.66 h; cefazolin off cycler : 23.09 +/- 5.6 h; P = 0.001; tobramycin on cycler : 14.27 +/- 4.53 h; tobramycin off cycler : 68. 5 +/- 26.47 h; P < 0.001). Mean serum and dialysate concentrations were above minimum inhibitory concentrations of susceptible organisms throughout the 24-h period for both drugs with intravenous administration. A model was developed to examine serum and dialysate concentrations after intermittent intraperitoneal administration of 15 mg/kg cefazolin and 0.6 mg/kg tobramycin. Model-predicted intraperitoneal cefazolin provides adequate serum and dialysate concentrations for 24 h. Intermittent intraperitoneal tobramycin doses must be 1.5 mg/kg for one exchange during the first day and then given as 0.5 mg/kg thereafter. It is concluded that the current empiric dosing recommendations for PD-related peritonitis may be adequate for cefazolin (15 to 20 mg/kg); however, tobramycin doses must be changed to 1.5 mg/kg intraperitoneally on day 1, then to 0.5 mg/kg intraperitoneally thereafter in APD patients.

Chromium picolinate toxicity

OBJECTIVE

To describe a case of toxicity secondary to chronic ingestion of 6-12 times the recommended daily allowance of over-the-counter (OTC) chromium picolinate.

CASE SUMMARY

A 33-year-old white woman presented with weight loss, anemia, thrombocytopenia, hemolysis, liver dysfunction (aminotransferase enzymes 15-20 times normal, total bilirubin 3 times normal), and renal failure (serum creatinine 5.3 mg/dL; blood urea nitrogen 152 mg/dL). She had ingested chromium picolinate 1200-2400 microg/d for the previous 4-5 months to enhance weight loss. The patient had chromium plasma concentrations 2-3 times normal. Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome were ruled out by clinical findings, peripheral blood smears, and a bone marrow biopsy. The patient was managed with supportive measures and received blood product transfusions and hemodialysis. Hemolysis stabilized and liver function improved over 6 days. Liver function returned to normal prior to discharge. Renal function began to return on day 12 and her serum creatinine on discharge was 1.3 mg/dL. One year later, all laboratory values were within normal limits.

DISCUSSION

Trivalent chromium is an essential trace element that is considered safe when ingested in normal quantities. Trivalent chromium compounds are used by patients to enhance weight loss, increase lean body mass, and/or improve glycemic control. Information regarding the toxicity of chromium picolinate is limited.

CONCLUSIONS

Chromium supplements may cause serious renal impairment when ingested in excess. Medication histories should include attention to the use of OTC nutritional supplements often regarded as harmless by the public and lay media.

Nonnarcotic analgesics: prevalence and estimated economic impact of toxicities

OBJECTIVE

To review and compare the risks of nonnarcotic analgesic toxicities in adults and estimate the relative healthcare costs of these toxicities, since direct comparison of costs is not possible.

DATA SOURCES

A MEDLINE search of the literature from 1969 to 1995 was used to identify pertinent data. Additional references were identified from articles obtained in the search. Information was obtained from prospective, retrospective, controlled, and uncontrolled studies; case reports; and review articles.

DATA EXTRACTION

Estimates of annual US costs of toxicities were extrapolated and synthesized from data from diagnosis-related groups, published information about the incidence of toxicity, or local data.

DATA SYNTHESIS

Chronic use of nonsteroidal antiinflammatory drugs (NSAIDs) is associated with a high incidence of acute renal toxicity and gastrointestinal toxicity. The most common problems associated with acetaminophen use are hepatoxicity after acute problems ingestion of large doses (> 10 g) or habitual use of smaller doses (< 4 g), particularly in alcoholic patients, and chronic analgesic nephropathy. Aspirin use is associated with a high incidence of gastrointestinal and acute renal toxicity in certain patient groups. Available data suggest that acetaminophen, used intermittently, remains the nonnarcotic analgesic of choice in many patient populations, including those with impaired renal function, gastrointestinal disease, and bleeding disorders. Estimated annual US costs associated with the toxicities of acetaminophen (excluding hepatotoxicity), aspirin (acute upper gastrointestinal bleeding only), and NSAIDs (excluding non-upper gastrointestinal hemorrhagic complications and hepatotoxicity) are about $51.5 million, $358.6 million, and $1.35 billion, respectively.

CONCLUSIONS

Intermittent use of most nonnarcotic analgesics produces a small risk of chronic renal or hepatic toxicity. Gastrointestinal toxicity, especially upper gastrointestinal bleeding, remains a significant problem with NSAIDs and aspirin. Acetaminophen remains the nonnarcotic analgesic of choice for intermittent use by most patient groups. The toxicities associated with NSAIDs constitute about 72.6% of the total toxicities (costs $1.86 billion) caused by NSAIDs, acetaminophen, and aspirin.

Successful management of steroid-resistant nephrotic syndrome using ibuprofen

We report the first case of the use of ibuprofen for the management of steroid-resistant nephrotic syndrome. A 41 year-old man with nephrotic syndrome, secondary to focal segmental glomerulosclerosis, had persistent nephrotic range proteinuria despite aggressive treatment with steroids and cyclophosphamide. His steroid-resistant nephrotic syndrome resolved rapidly when he was serendipituously started on ibuprofen for the treatment of pericarditis. His proteinuria remained low at about 0.5 g/day over the next two years of treatment with ibuprofen and without any increase in his serum creatinine. He did not receive any ACE inhibitor or calcium channel blocker. An attempt to discontinue ibuprofen resulted in the relapse of his nephrotic syndrome. Upon restarting ibuprofen, his proteinuria decreased to less than 0.5 g/day again. We conclude that ibuprofen has been effective and safe for the management of nephrotic syndrome in this patient. However, careful monitoring is prudent to assess the potential adverse effects of ibuprofen on renal function with prolonged use.

Severe accidental dapsone overdose

Acute poisoning from excessive dapsone (4,4-diaminodiphenylsulfone) intake in uncommon in the United States; no cases were reported during 1992. However, with the increasing use of dapsone for diseases other than leprosy and dermatitis herpetiformis, such as acne vulgaris, psoriasis, and Pneumocystis carinii pneumonia infection in acquired immunodeficiency syndrome, clinicians should be aware of potential toxicities. This report describes a case of accidental dapsone intoxication resulting in severe cyanosis with a modest elevation in methemoglobin concentration.

Drug poisoning patterns: the Albany experience, 1978 and 1988

This study retrospectively compares the demography and patterns of poisonings and their local variations among patients admitted to Albany Medical Center Hospital in the years 1978 and 1988. An increase in the number of admissions during this period of time, and an apparent substantial change in the pattern of poisonings was observed; in addition, the gender difference observed in 1978 disappeared. Although street drugs were a common source of poisoning, the resulting morbidity and mortality was low. The use of extracorporeal drug removal procedures appears to have declined in this institution in the two years evaluated.

Serum factor from patients with chronic renal failure enhances polymorphonuclear leukocyte oxidative metabolism

Sera from patients with chronic renal failure (CRF) contain a factor(s) which enhances the oxidative metabolism of polymorphonuclear leukocytes (PMN) as assessed by chemiluminescence (CL), superoxide anion generation, and hexose monophosphate shunt activity. PMN oxidative metabolic activity was higher in CRF sera than in sera from hospitalized patients with normal renal function or in sera from normal healthy subjects. The enhancement occurred regardless of whether PMN were unstimulated or were stimulated by a nonspecific soluble membrane stimulant (phorbol myristate acetate), or by opsonized Candida albicans. The enhanced CL was significantly reduced in their sera after normal renal function was restored with successful renal transplantation. This CL-enhancing factor was also detected in dialysate fluids from CRF patients and in urine from normal healthy subjects. When serum, urine, dialysate fluids of these CRF patients were fractionated by Sephadex G-25 column chromatography, the specific fraction responsible for enhanced CL was found in the molecular weight range less than 1,000 daltons, and is an ethanol extractable substance with natural fluorescence. Our findings suggest that the enhanced PMN stimulatory activity in CRF serum is specifically associated with renal dysfunction and can be useful, along with other conventional parameters, for monitoring the progression of CRF.