Urine acidifying agents

Concomitant use of urine-acidifying agents (ammonium chloride, ascorbic acid) decreases urine pH and sulfonamide solubility, thus increasing risk of crystalluria. Concomitant use with antibiotics that alter intestinal flora may interfere with conversion of sulfasalazine to sulfapyridine and 5-aminosalicylic acid, decreasing its effectiveness. 

B. Proteus species produce urease (A) that produces ammonia and urea, alkalizing urine. Urine requires acidification for effective therapy. Hippuric (B), mandelic, or ascorbic acids or methionine are urinary acidifying agents. The normal acidic urinary environment is disturbed by recurrent Proteus in-... 

Urinary antiseptics are oral drugs that are rapidly excreted into the urine and act there to suppress bacteriuria. The drugs lack systemic antibacterial effects but may be toxic. Urinary antiseptics are often administered with acidifying agents, because low pH is an independent inhibitor of bacterial growth in urine. 

Dietary modification depends on the type of stones formed. The formation of calcium phosphate stones may be lessened by a calcium- and phosphorus-restricted diet, and by aluminum gel which diminishes the absorption of phosphoms. Modification of the urine pH also prevents the formation of kidney stones. An acid urine helps prevent stones of calcium and magnesium phosphate and carbonates, while an alkaline urine helps prevent oxalate and uric acid stones. The diet should support therapy with alkalinizing or acidifying agents by supplying acid-producing or alkaline-producing foods. Also the formation of uric acid stones may be lessened by a purine-restricted diet. 

Methenamine (hexamethylenetetramine) is an aromatic acid that is hydrolyzed at an acid pH (<6) to liberate ammonia and the active alkylating agent formaldehyde, which denatures protein and is bactericidal. Methenamine is usually administered as a salt of either man-delic (Mandelamine) or hippuric Hiprex, Urex) acid. Not only do these acids acidify the urine, which is necessary to generate formaldehyde, but also, the resulting low urine pH is by itself bacteriostatic for some organisms. 

A stereoselective GC method for determination of etodolac enantiomers in human plasma and urine was first reported as a preliminary method [35], and then as a validated method [36]. Sample preparation involved addition of (S)-(+)-naproxen (internal standard) and sodium hydroxide to diluted plasma or urine. The samples were washed with diethyl ether, acidified with hydrochloric acid, and extracted with toluene. ( )-(+)-naproxen was used as a derivatizing agent to form diastereomeric derivatives of etodolac. The gas chromatograph system used in this work was equipped with fused-silica capillary column (12 m x 0.2 mm i.d.) coated with high-performance cross-linked methylsilicone film (thickness 0.33 pm) and a nitrogen-phosphorous detector. The operating conditions were injector 250°C detector 300°C column 100-260°C (32 °C/min). 

Intermittent self-catheterization with or without a concomitant anticholinergic agent is recommended in patients with large postvoid urine residual volumes (>100 mL) or when the urinary problem is hyporeflexic in nature (failure to empty). Patients with large postvoid residual volumes are at risk for developing urinary tract infections and often are prescribed urinary acidifiers such as vitamin C or antiseptics such as methenamine mandelate to prevent infections. 

The GC/MS-MS methods for the quantitative determination of nerve agents have been reported (Driskell ct al 2002 Barr etal., 2004). The difference between the two methods is that in the study by Driskell etal., the urine sample.s were concentrated by forming an azeotrope with acetonitrile, whereas in the study by Barr et al the acidified urine samples were extracted into ether acetonitrile. The samples were derivalized by methylalion with diazomeihane and analyzed by GC/MS-MS. 

Liquid-liquid extraction (LLE) is one of the oldest and most common types of sample preparation utilized in analytical chemistry. This extraction technique is based upon the solubility/affinity of an analyte between two immiscible liquids, typically composed of one aqueous and one organic layer. In a recent review, John et al. [3] discussed the application of LLE for the sample preparation of alkyl phosphonic acids in a variety of sample matrices including water, serum and acidified urine. Modifications to typical LLEs have resulted in miniaturization, preconcentration and added selectivity through introduction of ion-pairing agents. Xu et al. 14] developed an ion-pairing liquid-liquid-liquid... 

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