Oral regimen for high dose methotrexate urine alkalinization: a systematic review and meta-analysis.

OBJECTIVE: Urine alkalinization prevents nephrotoxicity in patients receiving high-dose methotrexate (HDMTX). While the standard approach involves IV sodium bicarbonate, alternative oral bicarbonate regimens are crucial in drug shortages and outpatient settings. This study aims to review the efficacy and safety of such regimens. METHODS: PubMed, WOS, and Scopus were systematically searched using the PRISMA protocol for relevant studies involving human subjects, including randomized clinical trials, retrospective, prospective, cohort, case reports, and case series studies. There were no restrictions on language, time, or age group. Qualified and eligible papers were used to extract data on efficacy and safety indicators, and the final relevant records were assessed for quality using the Risk of Bias in Non-Randomized Studies-of Interventions (ROBINS-I) assessment tool. RESULTS: 12 studies with 1212 participants were included in the systematic review, with pooled data from 8 studies used for meta-analysis. No significant differences in mean differences (MDs) or odds ratio (OR) were found after the oral bicarbonate regimen, except for when urine pH fell to < 7 (MD: 0.91, 95% CI: 0.32, 1.5, P < 0.05) and the incidence of diarrhea (OR: 2.92, 95% CI: 1.69, 5.05, P < 0.05). CONCLUSION: An oral bicarbonate regimen is a safe and effective way to alkalize HDMTX urine, providing a viable and cost-effective alternative to IV protocols. Further prospective multicenter studies are necessary. Systematic review registration identifier: CRD42023379666.

Incidence of rebound salicylate toxicity following cessation of urine alkalinization.

INTRODUCTION: Management of patients with salicylate toxicity frequently requires urine alkalinization to enhance excretion of salicylate. One strategy for determining when to stop urine alkalinization is to wait for two consecutive serum salicylate concentrations to be less than 300 mg/L (2.17 mmol/L) and declining. When alkalinization of the urine ceases, a rebound in serum salicylate concentration can occur from tissue redistribution or delayed gastrointestinal absorption. Whether this can lead to rebound toxicity is not well understood. METHODS: This was a single-center, retrospective review of cases with a primary ingestion of acetylsalicylic acid reported to the local poison center over a five-year period. Cases were excluded if the product was not listed as the primary ingestion or if there was no serum salicylate concentration documented after discontinuation of intravenous sodium bicarbonate infusion. The primary outcome was the incidence of serum salicylate rebound to a concentration greater than 300 mg/L (2.17 mmol/L) after discontinuation of intravenous sodium bicarbonate infusion. RESULTS: A total of 377 cases were included. Of these, eight (2.1%) had a serum salicylate concentration increase (rebound) after stopping the sodium bicarbonate infusion. All these cases were acute ingestions. Five of the eight cases had rebound serum salicylate concentrations that were greater than 300 mg/L (2.17 mmol/L). Of these five patients, only one reported recurrent symptoms (tinnitus). Prior to stopping urinary alkalinization, the last or the last two serum salicylate concentrations were less than 300 mg/L (2.17 mmol/L) in three and two cases, respectively. CONCLUSIONS: In patients with salicylate toxicity, the incidence of rebound in serum salicylate concentration after cessation of urine alkalinization, is low. Even if serum salicylate rebounds to supratherapeutic concentrations, symptoms are often absent or mild. Routine repeat serum salicylate concentrations after urine alkalinization is stopped may be unnecessary unless symptoms recrudesce.

Retrospective evaluation of sodium acetate use for urine alkalinization in patients receiving high dose methotrexate.

PURPOSE: Methotrexate is an antifolate agent used in treatment of several malignancies. Many toxicities accompany methotrexate that are minimized with urine alkalinization. Parenteral sodium bicarbonate is the historical standard alkalinizing agent, but use has been limited by intermittent shortages. However, intravenous sodium acetate may be considered as a chemically equivalent alternative. The primary objective of this study is to determine the efficacy of sodium acetate versus sodium bicarbonate for urine alkalinization for high-dose methotrexate (HDMTX). METHODS: This is a retrospective cohort study including adults admitted to Barnes-Jewish Hospital to receive HDMTX for lymphoma, breast cancer with leptomeningial spread, or osteosarcoma. Patients must have received intravenous sodium acetate or sodium bicarbonate alkalinization. RESULTS: Of 192 HDMTX encounters, 154 (sodium bicarbonate, n = 86; sodium acetate, n = 68) were evaluated for efficacy and safety. Safety outcomes were not significantly different between groups except for higher peak methotrexate level in the bicarbonate group (2.9 mcmol/L vs. 1.7 mcmol/L, p = 0.023), and increased incidence of grade 3-4 ALT in the sodium bicarbonate group (23.5% vs. 9%, p = 0.02). Time from alkalinizer initiation to pH ≥7 was significantly shorter with sodium bicarbonate (4 vs. 5.15 h, p = 0.021). Nonetheless, outcomes such as length of stay (4.4 vs. 4 days respectively, p = 0.037) and time to methotrexate clearance (3.6 vs. 3.2 days respectively, p = 0.023) reveal that inpatient time was shorter with sodium acetate overall. CONCLUSION: This retrospective analysis suggests that sodium acetate has similar efficacy and safety to sodium bicarbonate for alkalinization and may be considered as an alternative in future shortage situations.

Evaluation of an oral sodium bicarbonate protocol for high-dose methotrexate urine alkalinization.

PURPOSE: Intravenous (IV) sodium bicarbonate is considered standard therapy for high-dose methotrexate (HDMTX) urine alkalinization. Due to a national IV sodium bicarbonate shortage, an oral (PO) sodium bicarbonate protocol was implemented by Alberta Health Services (AHS) for HDMTX urine alkalinization. This study aims to evaluate the efficacy and safety of the PO sodium bicarbonate protocol compared to IV sodium bicarbonate for HDMTX urine alkalinization. METHODS: A retrospective chart review of adult patients who received HDMTX (> 500 mg/m2) with sodium bicarbonate for urine alkalinization at 4 hospitals in Alberta was conducted. Patients who received IV sodium bicarbonate between January and June 2017 and PO sodium bicarbonate between July and December 2017 were compared for the primary outcome of time to methotrexate clearance. RESULTS: A total of 84 and 78 HDMTX cycles were included in the IV and PO cohorts, respectively. No difference in time to methotrexate clearance was seen between the IV and PO cohorts, 91.6 (± 35.4) hours and 95.2 (± 44) hours respectively; p = 0.5. The proportion of HDMTX cycles that experienced a > 25% increase in serum creatinine was not statistically significant, IV protocol 12% and PO protocol 5%; p = 0.13. Nausea and emesis occurred more frequently in the PO cohort than the IV cohort, though rarely resulted in refused doses or change to alternate sodium bicarbonate formulations. CONCLUSIONS: The results of this study indicate that the AHS PO sodium bicarbonate protocol was no different in time to methotrexate clearance or rates of increased serum creatinine when compared to IV sodium bicarbonate.

Evaluation of methotrexate clearance with an enteral urine alkalinization protocol for patients receiving high-dose methotrexate.

PURPOSE: High-dose methotrexate is a cytotoxic agent used to treat several malignancies. Urine alkalinization with sodium bicarbonate and hyperhydration are given with methotrexate to prevent drug precipitation in the kidneys. Due to a nationwide intravenous sodium bicarbonate shortage, an enteral-based urine alkalinization protocol was instituted. This study compared outcomes and adverse effects between the previously used intravenous and newly implemented enteral protocols. METHODS: Single center retrospective cohort study comparing parenteral and enteral urine alkalinization for patients that received methotrexate doses ≥ 500 mg/m2 between 1 April 2016 and 1 October 2018. The primary endpoint was time to methotrexate clearance. Secondary outcomes included length of stay, time to administration of methotrexate, amount of sodium bicarbonate utilized, toxicities of methotrexate, and protocol-associated adverse effects. RESULTS: There were 67 patients included in the study for a total of 195 infusions. The average time to methotrexate clearance between the two cohorts was similar (parenteral 88 h vs. enteral 98 h p = 0.06). Likewise, length of stay was not different between the two cohorts (p = ns). The enteral cohort methotrexate's doses were initiated faster and received significantly less intravenous sodium bicarbonate when compared to the parenteral cohort (p = 0.04). Rates of acute kidney injury, neutropenia, hepatotoxicity, and mucositis were similar between the two groups. There were higher rates of diarrhea and low serum bicarbonate values in the enteral cohort. CONCLUSION: This study supports the ability to conserve intravenous sodium bicarbonate by using an enteral-based urine alkalization regimen for HD methotrexate, with no difference in outcomes or toxicity.

Ultrastructural evaluation of urine alkalinization versus hydration on colistin-induced nephrotoxicity.

OBJECTIVES: Colistin is a vital antibiotic used in multidrug-resistant infections. Its most important side effect is nephrotoxicity. Colistin is a weak acid. This study aims to evaluate whether urine alkalinization is protective in the nephrotoxicity of colistin. METHODS: Twenty-eight male Sprague-Dawley rats were divided into groups. Group I (n = 4) was injected with intramuscular distilled water twice a day for 7 days. Group II (n = 8) was injected with 750,000 IU/kg/day colistin for 7 days. Group III (n = 8) was injected with the same dose of colistin after their urinary pH was ≥7 through the addition of bicarbonate in their drinking water. Group IV (n = 8) was injected with the same dose of colistin after their urine density fell below 1010 through the addition of NaCl molds in their food and 12.6 mg/L NaCl in their drinking water. RESULTS: According to tubular degenerations (scored 0-5), group I scored 0, group II scored 4.25, group III scored 2, and group IV scored 1.5. In groups III and IV, protection was achieved (p = 0.001). The bicarbonate group was not superior to the NaCl group (p = 0.789). In transmission electron microscopy, group III had more microvilli integrity and autophagic vacuoles compared to group IV. Group IV had mitochondrial swelling and cristae lysis. A lower urine density was related to lower tubular scores (p = 0.001). CONCLUSIONS: Colistin was highly nephrotoxic without protection. Light microscopy findings revealed that urinary alkalinization and NaCl hydration were similarly protective. Urine alkalinization further prevents ultrastructural changes as revealed by electron microscopy.

Safety and efficacy of a urine alkalinization protocol developed for high-dose methotrexate patients during intravenous bicarbonate shortage.

PURPOSE: Urinary alkalinization with intravenous sodium bicarbonate is standard during high-dose methotrexate administration. Due to a national intravenous sodium bicarbonate shortage, a urinary alkalinization protocol involving hyperhydration with intravenous fluids, oral bicarbonate, and intravenous or oral acetazolamide was utilized from 10 April to 30 May 2017 ("shortage protocol"). This study compared outcomes between protocols. METHODS: A single-center, retrospective chart review was conducted for adults who received methotrexate ≥500 mg/m2 on ≥ two occasions, at least once during each protocol, between 19 February and 19 July 2017. RESULTS: Eighteen patients (50% male), median age 65 years, received 76 total high-dose methotrexate cycles. Shortage protocol was used in 37 cycles (48.7%). Mean time to methotrexate clearance did not differ between groups (p = ns). Mean time to urinary alkalinization and duration of hospitalization were not statistically different (p = 0.49 and 0.23, respectively). Average total bicarbonate administered per 24 hours was higher in standard protocol (p < 0.05), but hydration rates were similar (p = 0.73). Creatinine clearance and urine output on days 1 and 2 post-high-dose methotrexate did not significantly differ (creatinine clearance day 1, p = 0.27; creatinine clearance day 2, p = 0.55; urine output day 1, p = 0.62; urine output day 2, p = 0.60). Interruptions in alkalinization were significantly higher during shortage (0.41 ± 0.75 instances of urine pH < 7 during standard vs. 1.3 ± 1.7 under shortage, p < 0.05).

Effects of urine alkalinization with sodium bicarbonate orally on lower urinary tract symptoms in female patients: a pilot study.

INTRODUCTION AND HYPOTHESIS: In this study, we planned to explore the effects of sodium bicarbonate orally (NaHCO3) treatment on female patients with lower urinary tract symptoms (LUTS) who have acidic urine pH values (<6). METHODS: NaHCO3 was given orally to 33 female patients for 4 weeks at a dose of 2 × 4 g/day. Laboratory values, bladder diary, the Patient Perception of Bladder Condition Score (PPBC), Patient Perception of Intensity of Urgency Scale (PPIUS), Overactive Bladder-Validated 8-question Awareness tool (OAB-V8), Pelvic Pain and Urgency & Frequency Patient Symptom Scale tests (PUFSS), and the King's Health Questionnaire (KHQ) scores before and after treatment were compared. RESULTS: A significant increase was detected in urine pH values measured after treatment (5.31 ± 0.52 to 7.2 ± 0.66, p < 0.001), but not in blood pH values (7.369 ± 0.33 to 7.384 ± 0.28, p = 0.14). After treatment, a significant decrease was detected in daily frequency, nocturia, urgency, and urge incontinence prevalence (p < 0.001,p = 0.003, p < 0.001, p = 0.002, respectively) and PPBC, PPIUS, PUFSS, and OAB-V8 symptom scores (p = 0.004, p = 0.002, p < 0.001, p < 0.001, respectively). A significant decrease was detected in all KHQ subunit scores. CONCLUSION: Urine alkalinization with NaHCO3 orally in female patients with LUTS and acidic urine pH has a significant level of positive effects on symptoms and symptom scores. Our results show that this new treatment modality-which is inexpensive, easy to use, and has a low side-effect profile is effective in this chronic patient group.

Comparison of enteral and parenteral methods of urine alkalinization in patients receiving high-dose methotrexate.

Purpose Hyperhydration and urinary alkalinization is implemented with all high-dose (HD)-methotrexate infusions to promote excretion and prevent precipitation of methotrexate in the renal tubules. Our institution utilized enteral alkalinizing agents (sodium bicarbonate tablets and sodium citrate/citric acid solution) to alkalinize the urine of patients receiving HD-methotrexate during a parenteral sodium bicarbonate and sodium acetate shortage. The purpose of this study is to establish the safety and efficacy of the enteral route for urine alkalinization. Methods A single-center, retrospective, cohort study was conducted comparing cycles of HD-methotrexate using enteral alkalinizing agents to parenteral sodium bicarbonate. The primary objective was to compare the time, in hours, from administration of first inpatient administered dose of alkalinizing agent to time of achieving goal urine pH. Secondary objectives evaluated total dose of sodium bicarbonate required to achieve goal urine pH, time from start of urine alkalinizing agent until time of achieving methotrexate level safe for discharge, and toxicities associated with methotrexate and the alkalinizing agents. Results A total of 118 patients were included in this study, equally divided into two cohorts based on parenteral versus enteral routes of administration. No statistical difference was determined between the two cohorts regarding time to goal urine pH (6.5 h versus 7.9 h, P = 0.051) or regarding time to methotrexate level deemed safe for discharge (63.5 h versus 62.5 h, p = 0.835). There were no significant differences in methotrexate-induced toxicities. Conclusion Our study found enteral routes of urine alkalinization to be a viable alternative to the traditional parenteral sodium bicarbonate, especially during parenteral sodium bicarbonate and acetate shortages.

Sodium bicarbonate protects uranium-induced acute nephrotoxicity through uranium-decorporation by urinary alkalinization in rats.

To evaluate the effectiveness of sodium bicarbonate (SB) in removing uranium and protecting animals from uranium toxicity, we intramuscularly administered 1 mg/kg of uranyl nitrate to 8-wk-old male SD rats, and 20 min after administration of uranyl nitrate, the animals were given a single oral administration of SB at 0.1, 0.3 or 1 g/kg. The SB treatment at a dose of 0.3 g/kg or more raised the pH of the rats' urine until 4 h after treatment, and it significantly reduced the uranium amounts in the kidneys at 1 day after treatment. In another experiment, rats were intramuscularly administered 1 mg/kg of uranyl nitrate, and 20 min later, the animals were treated with sodium bicarbonate (0.1 or 1 g/kg). The rats were autopsied at 1, 3 and 7 days after uranium treatment. High-dose SB resulted in a significant increase in urinary uranium excretion in the first 24 h and a reduction of uranium deposition in the kidneys and femurs, and it also significantly suppressed uranium-induced renal toxicity, as shown by both histopathology and clinical chemistry at 3 days after uranium treatment. Low-dose SB did not show such marked effects. Our findings demonstrated that the uranium decorporation effect of sodium bicarbonate was observed at the dosage showing urine alkalinization in rats and that decorporation effect of sodium bicarbonate might be beneficial if it is administered immediately after incorporation of soluble uranium.

Excretion of urinary exosomal AQP2 in rats is regulated by vasopressin and urinary pH.

Urinary exosomes are small vesicles secreted into urine from all renal epithelial cell types and known to contain proteins that are involved in renal secretion and reabsorption. Among these proteins, urinary exosomal aquaporin-2 (AQP2) has been suggested to be useful for diagnosis of renal disease. However, the mechanisms underlying the excretion of urinary exosomal AQP2 are largely unknown. In this study, we examined the mechanisms of urinary exosomal AQP2 excretion in vivo, using diuretics including furosemide (FS), an inhibitor of the sodium-potassium-chloride symporter; acetazolamide (ACTZ), an inhibitor of carbonic anhydrase; OPC-31260 (OPC), a vasopressin type 2 receptor antagonist; and NaHCO3, a urinary alkalizing agent. Samples of urine from rats were collected for 2 h just after treatment with each diuretic, and urinary exosomes were isolated by ultracentrifugation. Urinary exosomal AQP2 excretion was dramatically increased by treatment with FS accompanied by urine acidification or with ACTZ accompanied by urine alkalization. Immunohistochemistry showed that apical localization of AQP2 was clearly evident and the plasma vasopressin level was increased after each treatment. Although treatment with OPC alone had no significant effect, coadministration of OPC completely inhibited the FS-induced and partially reduced the ACTZ-induced responses, respectively. Treatment with NaHCO3 increased the excretion of urinary exosomal AQP2 accompanied by urine alkalization. This increased response was partially inhibited by coadministration of OPC. These data suggest that an increased plasma level of vasopressin promoted the excretion of urinary exosomal AQP2 and that urine alkalinization also increased it independently of vasopressin.

Is There Any Relationship Between Hematuria in Rhabdomyolysis and Renal Injury?

PURPOSE: In previous literature, urinalysis in rhabdomyolysis has been known to be positive for occult blood, but without overt hematuria. Recently, however, we have reported hematuria in patients with doxylamine overdose in association with rhabdomyolysis. We wanted to determine whether the hematuria resulted from the toxicity of doxylamine itself or from rhabdomyolysis, and further to investigate the relationship between hematuria, acute renal failure (ARF), and the presence of urine alkalinization. METHODS: The medical records of 167 patients diagnosed with rhabdomyolysis who were admitted to Kyung Hee Medical Center between 2000 and 2004 were retrospectively examined. Patients without laboratory results 3 times a day, patients with inaccurate records, and patients with diseases that could cause hematuria were excluded, leaving 79 patients for evaluation. The relationship between laboratory results, occurrences of ARF and urine alkalinization were compared and assessed. RESULTS: Hematuria was observed in 76 of 79 patients with rhabdomyolysis, irrespective to the cause of rhabdomyolysis. The percentage of dysmorphic RBC was 58% and MCV (mean corpuscular volume) was 76+/-15 fL found in hematuria. Urine alkalinization was not associated with the presence of hematuria. The laboratory results of ARF patients compared to those of non-ARF patients showed a significant difference in the average urine pH, and ARF with rhabdomyolysis was not associated with muscle enzyme levels but rather was associated with the duration of hematuria. CONCLUSION: Hematuria was found in patients with rhabdomyolysis irrespective of the cause of rhabdomyolysis. Therefore, hematuria is associated with rhabdomyolysis rather than doxylamine intoxication. The occurrence of hematuria in rhabdomyolysis is unrelated to urine alkalinization. The duration of hematuria in ARF group was significantly longer than in non-ARF group. It is therefore important to bear in mind the possibility that ARF will develop when hematuria lasts for a long time. Furthermore, we feel that additional prospective studies and investigations into the mechanism of hematuria in rhabdomyolysis should be done.