Urinary elimination

The half-life for elimination of a single oral dose of 0.00114 g/kg 3H 2,3,7,8-TCDD in a human volunteer was calculated as 5.8 years (Poiger and Schlatter 1986). The excretion in feces was high during the first few days (up to day 6) probably because of elimination of unabsorbed material. During these first few days, about 12% of the administered dose was excreted. However, during days 7-125 only about 3.5% of the administered dose was eliminated. Urinary levels of radioactivity did not exceed the background levels. 

Several other documented relapses while patients are under therapy with 5-fluoro-cytosine for cryptococcal meningitis have been described, and, in some cases have been attributed to development of resistance during therapy. Oral doses of 2 to 5 grams a day of 5-fluorocytosine have been successful in reducing urinary counts of Candida in some instances, and have apparently eliminated urinary candidiasis in other cases.20 Serum binding of 5 fluorocytosine was calculated to be approximately 50 however the fungicidal effect of 5-fluorocytosine on Candida was enhanced vitro by the addition of serum to the media, urine appeared to inhibit the jjx vitro action of 5-fluorocytosine. ... 

A 1,8-naphthyridine, nalidixic acid (39), shows clinically useful antibacterial activity against Gram-negative bacteria as such, the drug is used in the treatment of infections of the urinary tract. Condensation of ethoxymethylenemalonate with 2-amino-6-methylpyridine (36) proceeds directly to the naphthyri-dine (38) the first step in this transformation probably involves an addition-elimination reaction to afford the intermediate, 37. W-Ethylation with ethyl iodide and base followed by saponification then affords nalidixic acid (39). 

The pharmacokinetics of azacitidine shows that it is rapidly absorbed after s.c. administration with the peak plasma concentration occurring after 0.5 h. The bioavailability of s.c. azacitidine relative to i.v. azacitidine is approximately 89%. Urinary excretion is the primary route of elimination of azacitidine and its metabolites. The mean elimination half-lives are about 4 h, regardless of i.v. or s.c. administration. 

D Impaired Urinary Elimination related to adverse drug reaction of the sulfonamides... 

Maintaining Adequate Fluid Intake and Output Because one adverse reaction of the sulfonamide dragp is altered elimination patterns, it is important that the nurse helps the patient maintain adequate fluid intake and output. The nurse can encourage patients to increase fluid intake to 2000 mL or more a day to prevent crystal-luria and stone formation in the genitourinary tract, as well as to aid in the removal of microorganisms from the urinary tract. It is important to measure and record the intake and output every 8 hours and notify the primary health care provider if the urinary output decreases or the patient fails to increase his or her oral intake... 

Q Impaired Urinary Elimination related tourinary tract intedion... 

Affecting the rate of drug elimination by increasing urinary pH (eg, the excretion of salicylates is increased, whereas excretion of quinidine and amphetamines is decreased)... 

The concentration of a- and P-endosulfan in the urine of a pest control worker who wore protective equipment peaked at 0.2 days (approximately 5 hours) after completing a 25-minute application of endosulfan in a greenhouse, declined to control levels by about 1.5 days postexposure, and remained at levels comparable to controls until the end of sampling at 3-days postexposure (Arrebola et al. 1999). Assuming first-order elimination, the urinary elimination half-Ufe was estimated to be 0.94 days for a-endosulfan and 1.16 days for p-endosulfan no endosulfan metabolite was detected in any urine sample. 

Following inhalation exposure to trichloroethylene in humans, the unmetabolized parent compound is exhaled, whereas its metabolites are primarily eliminated in the urine. Excretion of trichloroethylene in the bile apparently represents a minor pathway of elimination. Balance studies in humans have shown that following single or sequential daily exposures of 50-380 ppm trichloroethylene, 11% and 2% of the dose was eliminated unchanged and as trichloroethanol, respectively, in the lungs 58% was eliminated as urinary metabolites and approximately 30% was unaccounted for (Monster et al. 1976, 1979). Exhaled air contained notable concentrations of trichloroethylene 18 hours after exposure ended because of the relatively long half-life for elimination of trichloroethylene from the adipose tissue (i.e., 3.5-5 hours) compared to other tissues (Fernandez et al. 1977 Monster et al. 1979). 

The primary urinary metabolites of trichloroethylene in humans are trichloroethanol, trichloroethanol glucuronide, and TCA (Monster et al. 1979 Nomiyama and Nomiyama 1971 Sato et al. 1977). The halftime for renal elimination of trichloroethanol and trichloroethanol glucuronide has been determined in several studies to be approximately 10 hours following trichloroethylene exposure (Monster et al. 1979 Sato et al. 1977). The urinary excretion of TCA is much slower, and data from several studies indicate that the halftime of urinary TCA is approximately 52 hours because the metabolite is very tightly and extensively bound to plasma proteins (Monster et al. 1976 Sato et al. 1977). 

Finally, the fact that anthocyanins can reach the brain represents a beginning of an explanation of the purported neuroprotection effects of anthocyanins. Anthocyanins may be eliminated via urinary and biliary excretion routes. " The extent of elimination of anthocyanins via urine is usually very low (< 0.2% intake) in rats and in humans, indicating either a more pronounced elimination via the bile route or extensive metabolism. As mentioned earlier, in the colon, non-absorbed or biliary excreted anthocyanins can be metabolized by the intestinal microflora into simpler break-down compounds such as phenolic acids that may be (re)absorbed and conjugated with glycine, glucuronic acid, or sulfate and also exhibit some biological... 

There was a significant negative correlation between (log) admission urinary PCP level and self-reported time since last PCP use (r= -0.53, p<0.001). Visual inspection of a graph of these two variables suggested a possible biphasic elimination curve, with the initial phase having a half-life of 5 to 7 days, and the later phase a half-life of about 30 days. However, formal curve fitting of these data to standard pharmacokinetic models (using BMDP... 

Urine is the principal excretory route for elimination of diisopropyl methylphosphonate after oral administration to mice, rats, pigs, mink, or dogs (Hart 1976 Snodgrass and Metker 1992 Weiss et al. 1994). However, the rate of excretion differs among species. Peak urinary excretion of a single oral dose of 225 mg/kg [14C]-radiolabeled diisopropyl methylphosphonate occurred at 6 hours in mice,... 

Studies with rats treated orally with triaryl or trialkyl phosphate esters (which may be found in organophosphate ester hydraulic fluids) indicate that these compounds and their metabolites are readily excreted in the urine, bile, feces and, to a limited extent, in expired air (Kurebayashi et al. 1985 Somkuti and Abou-Donia 1990a Suzuki et al. 1984a Yang et al. 1990). Urinary excretion of metabolites appears to be the predominant elimination route in rats for tri-ort/zo-cresyl phosphate and tri-para-cresyl phosphate, but biliary excretion of parent material and metabolites is also important (Kurebayashi et al. 1985 NTP... 

Onset of side effects Urinary elimination Microbiological stability... 

When a drug is eliminated by both metabolism and urinary excretion, it is possible to calculate the metabolic clearance rate (MCR) by the difference between TCR and RCR ... 

Thus, the overall elimination rate constant (ke[) here is the sum of the urinary excretion rate constant (ke) and the metabolism rate constant (km) ... 

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