Urine concentration

There is an increased risk of cyclosporine toxicity when the drug is administered with acetazolamide. Decreased serum and urine concentrations of primidone occur when the drug is administered with acetazolamide. 

Cinoxacin is contraindicated in patients with known hypersensitivity to the individual drug and in patients with anuria. Cinoxacin is a Pregnancy Category B drug and should be used with caution during pregnancy and lactation. Cinoxacin is used with caution in patients with hepatic impairment. When cinoxacin is administered with probenecid, there is a risk for lowered urine concentration of cinoxacin. 

Brugnone F, Perbellini L, Giuliari M, et al. 1994. Blood and urine concentrations of chemical pollutants in the general population. Med Lav 85 370-389. 

Urine concentrations of PCP determined by enzyme immunoassay did not correlate with the state of intoxication at the time the urine sample was taken. The test was negative in 15 percent of 1,000 patients with clinical evidence of PCP toxicity, many of whom admitted taking PCP (McCarron et al. 1981a). Several of these negative urines were analyzed for PCP analogues none were found. 

Fluid restriction is generally unnecessary as long as sodium intake is controlled. The thirst mechanism remains intact in CKD to maintain total body water and plasma osmolality near normal levels. Fluid intake should be maintained at the rate of urine output to replace urine losses, usually fixed at approximately 2 L/day as urine concentrating ability is lost. Significant increases in free water intake orally or intravenously can precipitate volume overload and hyponatremia. Patients with stage 5 CKD require renal replacement therapy to maintain normal volume status. Fluid intake is often limited in patients receiving hemodialysis to prevent fluid overload between dialysis sessions. 

The maintenance of plasma volume and plasma osmolarity occurs through regulation of the renal excretion of sodium, chloride, and water. Each of these substances is freely filtered from the glomerulus and reabsorbed from the tubule none is secreted. Because salt and water intake in the diet may vary widely, the renal excretion of these substances is also highly variable. In other words, the kidneys must be able to produce a wide range of urine concentrations and urine volumes. The most dilute urine produced by humans is 65 to 70 mOsm/1 and the most concentrated the urine can be is 1200 mOsm/1 (recall that the plasma osmolarity is 290 mOsm/1). The volume of urine produced per day depends largely upon fluid intake. As fluid intake increases, urine output increases to excrete the excess water. Conversely, as fluid intake decreases or as an individual becomes dehydrated, urine output decreases in order to conserve water. 

Fig. 14.1 95th percentile of urine concentrations (pg/g creatinine corrected) for the US population aged 20-59 years, three NHANES surveys. Shaded blocks show 4-nitrophenol (methyl parathion) unshaded blocks show 3,5,6-tnchloro. v-pyndinol... 

Animal and human studies have demonstrated that rifaximin has very poor intestinal absorption after oral administration, so that blood and urine concentrations of rifaximin are practically undetectable [6], Rifaximin excretion is essentially exclusively by the fecal route [5]. Therefore, when rifaximin is administered by the oral route, it acts locally at the intestinal level and eliminates the bacterial organisms that are causing the infection. The important antibacterial activity of rifaximin appears to be directly related to the high intestinal concentration of the drug and inhibition of bacterial growth. The drug has... 

A complete physical examination and laboratory analysis are needed to rule out secondary causes and to assess kyphosis and back pain. Laboratory testing may include complete blood count, liver function tests, creatinine, urea nitrogen, calcium, phosphorus, alkaline phosphatase, albumin, thyroid-stimulating hormone, free testosterone, 25-hydroxyvitamin D, and 24-hour urine concentrations of calcium and phosphorus. Urine or serum biomarkers (e.g., cross-linked N-telopeptides of type 1 collagen, osteocalcin) are sometimes used. 

Several studies provided data on blood and urine concentrations of cyanide and thiocyanate following occupational exposures at low concentrations. These values are generally similar to those of smokers who have not been occupationally exposed to HCN. Whole-blood cyanide concentrations during... 

Individual metabolism cages are recommended for collecting urine and feces in oral dosing studies. Excreta should be collected for at least 5 elimination half-lives of the test substance. When urine concentrations will be used to determine elimination rates, sampling times should be less than one elimination half-life (taken directly from the bladder in IV studies) otherwise, samples should be taken at equal time intervals. 

Plasma-concentration data (and urine-concentration data, if collected) are analyzed to estimate the measures or parameters — such as AUC, peak concentration apparent... 

In a study of Casas et al. [155], 120 pregnant women and 30 of 4-year-old boys were involved. The median urine concentration of the 4-year-old boys (4.2 ng/mL) was approximately double of the median concentration of the pregnant women (2.2 ng/mL). Other different studies conducted in the USA have focused on children exposure [152, 217, 218]. In all three studies, detection frequency was more than 94% which demonstrates the ubiquitous exposure of the complete population. 

Figure Urine concentration-time curves of sulfadimidine (SDM), and its metabolites (N, CH2OH, SOH) in urine of a calf following intravenous administration of 100 mg SDM/kg.

In calves and cows, SDM was excreted by glomerular filtration minus tubular reabsorption its renal clearance was urine flow correlated, and amounts to half of the creatinine clearance. The SCH2OH hydroxy metabolite was excreted by glomerular filtration and partly by tubular secretion, whereas both Na-SDM and SOH were excreted predominantly by tubular secretion (15 . The main metabolite in urine SCH2OH was 23 to 55 % of the administered dose (Table III). The urine concentration—time curves for SDM and its metabolites are illustrated in Figure 7 for a high SDM dosage. 

Drug/Lab test interactions False-positive urine glucose reactions may occur with penicillin therapy if Clinitest, Benedict s Solution, or Fehling s Solution are used. It is recommended that enzymatic glucose oxidase tests (such as Clinistix or Tes-Tape) be used. Positive Coombs tests have occurred. High urine concentrations of some penicillins may produce false-positive protein reactions (pseudoproteinuria) with the P.870... 

Urine concentrations are considerably higher than serum concentrations. 

Urine concentration Reduced Near normal Normal adult values... 

Cephalosporins are the agents of choice in renal failure. They attain adequate urine concentrations despite severely impaired renal function and toxicity remains low with increased plasma levels. Quinolones are preferred over aminoglycosides due to aminoglycoside-related ototoxicity. 

Santucci B, Manna F, Cannistraci C, et al. 1994. Serum and urine concentrations in nickel-sensitive patients after prolonged oral administration. Contact Dermatitis 30 97-101. 

Trimethoprim is well absorbed from the GI tract, and peak blood levels are achieved in about 2 hours. Tissue levels often exceed those of plasma, and the urine concentration of trimethoprim may be 100 times that of the plasma. Trimethoprim readily enters the CSF if inflammation is present. The half-life of the drug is approximately 11 hours. Sulfamethoxazole (ti,2 = 10 hours) is frequently coadministered with trimethoprim in a fixed dose ratio of 1 5 (trimethoprim to sulfamethoxazole). 

R.C. Baseit, C.B. Steward, E. Shaskan, Determination of serum and urine concentrations of tranyicypromine by eiectron-capture gas-iiquid chromatography, J. Anai. Toxicoi. 1 (1977)215-217. 

Desmopressin (the synthetic analog of vasopressin) acts by increasing water retention and urine concentration in the distal tubules of the kidney. This drug is administered intranasally (20-40 pg or one to two sprays) using a unit-dose, spray pump delivery system. The duration of action is 10 to 12 hours. The medication is expensive. 

Data on drug abusers do not permit the construction of a dose-response curve. However, blood and urine concentrations of SNA after emergency hospitalization may permit some extrapolation to the quantities consumed. ... 

No reports were found in the open literature on methods to reduce the body burden of HDl after inhalation, oral or dermal exposures. No blood, tissue or urine concentrations of HDl have been reported... 

Vasopressin also plays an important role in the short-term regulation of arterial pressure by its vasoconstrictor action. It increases total peripheral resistance when infused in doses less than those required to produce maximum urine concentration. Such doses do not normally increase arterial pressure because the vasopressor activity of the peptide is buffered by a reflex decrease in cardiac output. When the influence of this reflex is removed, eg, in shock, pressor sensitivity to vasopressin is greatly increased. Pressor sensitivity to vasopressin is also enhanced in patients with idiopathic orthostatic hypotension. Higher doses of vasopressin increase blood pressure even when baroreceptor reflexes are intact. 

Tetracyclines are excreted mainly in bile and urine. Concentrations in bile exceed those in serum tenfold. Some of the drug excreted in bile is reabsorbed from the intestine (enterohepatic circulation) and may contribute to maintenance of serum levels. Ten to 50 percent of various tetracyclines is excreted into the urine, mainly by glomerular filtration. Ten to 40 percent of the drug is excreted in feces. Doxycycline and tigecycline, in contrast to other tetracyclines, are eliminated by nonrenal mechanisms, do not accumulate significantly and require no dosage adjustment in renal failure. 

Previously popular but of unproved value, forced diuresis may cause volume overload and electrolyte abnormalities and is not recommended. Renal elimination of a few toxins can be enhanced by alteration of urinary pH. For example, urinary alkalinization is useful in cases of salicylate overdose. Acidification may increase the urine concentration of drugs such as phencyclidine and amphetamines but is not advised because it may worsen renal complications from rhabdomyolysis, which often accompanies the intoxication. 

Distribution of penicillin antibiotics is limited to extracellular fluids, but inflammation may enhance their distribution into tissues. Penicillins are actively transported in kidney, brain, and liver. Most penicillins undergo minimal hepatic metabolism and are cleared from the plasma primarily by renal excretion. Secretion of penicillins by the renal tubules results in high urine concentrations and rapid elimination from the body (50). 

In dogs, absorption following oral administration tends to be poor. At similar oral doses, peak serum levels are lower and plasma levels are less persistent than those observed for methicillin. Following intramuscular administration, however, maximum concentrations in serum are reached within 30 min. In contrast to methicillin, liver is the main excretory pathway for nafcillin. Like most other penicillins, nafcillin undergoes biotransformation to a small extent. Parent compound and its metabolites are excreted in bile and urine. Concentrations of nafcillin in tissues tend to be higher and more persistent following parenteral administration than was the case for methicillin, obviously due to enterohepatic recirculation. 

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