Creatinine reactions

Representative Method Although each chemical kinetic method has its own unique considerations, the determination of creatinine in urine based on the kinetics of its reaction with picrate provides an instructive example of a typical procedure. 

Description of Method. Creatine is an organic acid found in muscle tissue that supplies energy for muscle contractions. One of its metabolic products is creatinine, which is excreted in urine. Because the concentration of creatinine in urine and serum is an important indication of renal function, rapid methods for its analysis are clinically important. In this method the rate of reaction between creatinine and picrate in an alkaline medium is used to determine the concentration of creatinine in urine. Under the conditions of the analysis, the reaction is first-order in picrate, creatinine, and hydroxide. 

Procedure. Prepare a set of external standards containing 0.5 g/L to 3.0 g/L creatinine (in 5 mM H2SO4) using a stock solution of 10.00 g/L creatinine in 5 mM H2SO4. In addition, prepare a solution of 1.00 x 10 M sodium picrate. Pipet 25.00 mL of 0.20 M NaOH, adjusted to an ionic strength of 1.00 M using Na2S04, into a thermostated reaction cell at 25 °C. Add 0.500 mL of the 1.00 x 10 M picrate solution to the reaction cell. Suspend a picrate ion-selective electrode in the solution, and monitor the potential until it stabilizes. When the potential is stable, add 2.00 mL of a... 

Since the reaction is carried out under conditions in which it is pseudo-zero-order in creatinine and OH , the rate constant, k, is... 

Creatinine The most widely used creatinine methods are based on reaction between creatinine and picrate ions formed in an alkaline medium. 

SuperchlorinationShock Treatment. Superchlorination or shock treatment of pool water is necessary since accumulation of organic matter, nitrogen compounds, and algae consumes free available chlorine and impedes disinfection. Reaction of chlorine with constituents of urine or perspiration (primarily NH" 4, amino acids, creatinine, uric acid, etc) produces chloramines (N—Cl compounds) which are poor disinfectants because they do not hydrolyze significantly to HOCl (19). For example, monochloramine (NH2CI) is only 1/280 as effective as HOCl against E. coli (20). 

Hypochlorous acid reacts very rapidly and quantitatively with a slight excess of free ammonia forming monochloramine, NH2CI, which reacts at a slower rate with additional HOCl forming dichloramine, NHCI2. Trichloramine is formed when three moles of HOCl are added per mole of ammonia between pH 3—4 (100). Hypochlorous acid in the form of chlorine or hypochlorite is used in water treatments to oxidize ammonia by the process of break-point chlorination, which is based on formation of unstable dichloramine. The instabiHty of NHCI2 is caused by presence of HOCl and NCl (101,102). The reaction is most rapid at a pH of about 7.5 (103). Other nitrogen compounds such as urea, creatinine, and amino acids are also oxidized by hypochlorous acid, but at slower rates. Unstable iV-chloro compounds are intermediates in deammination of amino acids (104,105). 

More than half of the patients receiving this drug by the parenteral route experience some adverse reaction. Severe and sometimes life-threatening reactions include leukopenia (low white blood cell count), hypoglycemia (low blood sugar), thrombocytopenia (low platelet count), and hypotension (low blood pressure). Moderate or less severe reactions include changes in some laboratory tests, such as the serum creatinine and liver function tests. Other adverse reactions include anxiety, headache, hypotension, chills, nausea, and anorexia Aerosol administration may result in fatigue a metallic taste in the mouth, shortness of breath, and anorexia... 

RISK FOR INEFFECTIVE TISSUE PERFUSION RENAL When the patient is taking a drag tiiat is potentially toxic to die kidneys, die nurse must carefully monitor fluid intake and output. In some instances, die nurse may need to perform hourly measurements of die urinary output. Periodic laboratory tests are usually ordered to monitor the patient s response to therapy and to detect toxic drag reactions. Seram creatinine levels and BUN levels are checked frequentiy during the course of therapy to monitor kidney function. If the BUN exceeds 40 mg dL or if the serum creatinine level exceeds 3 mg cIL, the primary health care provider may discontinue the drug therapy or reduce the dosage until renal function improves. 

Older adults are at increased risk for adverse reactions from the antineoplastic drugs because of the increased incidence of chronic disease, particularly renal impairment or cardiovascular disease. When renal impairment is present, a lower dosage of the antineoplastic may be indicated. Creatinine clearance isused to monitor renal function in the older adult. Blood creatinine levels are likely to be inaccurate because of a decreased muscle mass in the older adult. 

The demand for monitoring common metabolites of diagnostic utility such as glucose, urea and creatinine continue to provide the impetus for a staggering research effort towards more perfect enzyme electrodes. The inherent specificity of an enzyme for a given substrate, coupled with the ability to electrochemically detect many of the products of enzymatic reactions initiated the search for molecule-selective electrodes. 

Adjust drug dosages based on the patient s creatinine clearance or evidence of adverse drug reactions or interactions. 

Fabiny, P.L. and Ertingshausen, E., Automated reaction rates method for determination of serum creatinine with the centrifichem, Clinical Chemistry, 17, 696-700, 1971. 

Knoevenagel condensation reaction of creatinine with aldehydes occurs rapidly under solvent-free reaction conditions at 160-170 °C using focused microwave irradiation (Scheme 6.18) [66],... 

Scheme 6.18 Knoevenagel condensation reaction of creatinine with aldehydes.

In resting muscle, creatine phosphate forms due to the high level of ATP. If there is a risk of a severe drop in the ATP level during contraction, the level can be maintained for a short time by synthesis of ATP from creatine phosphate and ADP. In a nonenzymatic reaction [6], small amounts of creatine and creatine phosphate cyclize constantly to form creatinine, which can no longer be phosphorylated and is therefore excreted with the urine (see p. 324). 

Repeated exposure of rats to an aerosol at a concentration of 470mg/m for 10 weeks caused only mild nasal irritation repeated exposure of rats to 77mg/m for 23 weeks resulted in elevated creatinine and boron content of the urine in addition to increased urinary volume. Conjunctivitis resulted when the dust was applied to the eyes of rabbits, probably the result of the exothermic reaction of boron oxide with water to form boric acid topical application of boron oxide dust to the clipped backs of rabbits produced erythema that persisted for 2-3 days. ... 

Adverse reactions to gold, especially dermatitis, can occur at plasma gold levels as low as 1 /ug/ml but impaired creatinine clearance, which is indicative of severe kidney damage, is rarely seen at plasma gold levels less than 4 [ig/ml (L14). The clinical value of plasma gold measurements must still be considered unsettled, despite the optimism of many investigators. 

Gl Gl symptoms are the most common reactions to miglitol. The incidence of diarrhea and abdominal pain tend to diminish considerably with continued treatment. Renal function impairment Plasma concentrations of miglitol in renally impaired volunteers were proportionally increased relative to the degree of renal dysfunction. Long-term clinical trials in diabetic patients with significant renal dysfunction (serum creatinine more than 2 mg/dL) have not been conducted. Treatment of these patients with miglitol is not recommended. 

Adverse reactions may include Stevens-Johnson syndrome pericardial effusion T-wave changes rebound hypertension (following gradual withdrawal in children) decreased initial hematocrit, hemoglobin and erythrocyte counts nausea vomiting temporary edema alkaline phosphatase/serum creatinine/BUN increase, hypertrichosis. 

Adverse reactions occurring in at least 3% of patients include hyperkalemia and dizziness, increased creatinine (more than 0.5 mg/dL). 

Adverse reactions occurring in at least 3% of aprepitant patients include the following Abdominal pain, anorexia, ALT/AST/BUN/Serum creatinine increased, asthenia/fatigue, constipation, dehydration, diarrhea, dizziness, epigastric discomfort, gastritis, headache, heartburn, hiccoughs, nausea, neutropenia, proteinuria, tinnitus, vomiting. 

High concentrations of cefoxitin (greater than 100 mcg/mL) may interfere with measurement of creatinine levels by the Jaffe reaction and produce false results. Cefotetan may also affect these measurements. 

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