Excretion half-life

Accumulation in Fish. The accumulation coefficient and excretion half-life of tri- and tetrabromo-benzenes, dibromo-toluene and xylene, are within a range expected on the basis of similar experiments Q ), and are summarized in Table II. 

Compound Concn. at water (vg/L) 48 h fish (wg/g) Accumulation coefficient Excretion half-life, h... 

Approved clinical investigations follow three phases. In Phase 1, about 100 to 200 people are exposed to the drug to determine the tolerance, absorption, excretion, half-life, and other pharmacologic reactions the preferred route of administration and the safe dosage. In Phase 2, initial trials are conducted on 500 to 1000 patients to assess the treatment or prevention of the specific disease. Additional animal studies to indicate safety may be conducted concurrently. If these preliminary studies demonstrate sufficient promise. Phase 3 clinical trials are performed with several thousand patients. 

Mechanism of Action An antihypertensive that blocks endothelin-l, the neurohormone that constricts pulmonary arteries. Therapeutic Effect Improves exercise ability and slows clinical worsening of pulmonary arterial hypertension (PAH). Pharmacokinetics Highlybound to plasma proteins, mainlyalbumin. Metabolized in the liver. Eliminated by biliary excretion. Half-life Approximately 5 hr. 

Pharmacokinetics Slowly, variably absorbed from the G1 tract. Widely distributed. Protein binding 91 %-99%. Metabolized in the liver. Primarily eliminated via biliary excretion. Half-life 10-15 hr. 

Pharmacokinetics Well absorbed following oral administration. Protein binding 10%-15%. Eliminated through metabolism, biliary excretion, and renal excretion. Half-life 3-4 hr... 

Young et al. (1977) exposed four volunteers to 50 ppm [180 mg/m ] 1,4-dioxane vapour for 6 h. It was rapidly taken up, with plasma levels reaching a plateau after 3 h. The major metabolite, P-hydroxyethoxyacetic acid (HEAA), was detected during the exposure period. At the end of the exposure, plasma levels of 1,4-dioxane fell with a half-life of 59 min. HEAA plasma levels reached their peak 1 h after the end of the exposure and fell thereafter with a half-life of 48 min. The absorption rate of 1,4-dioxane under these conditions was 76.1 mg/h and the total dose was 5.4 mg/kg. The dominant route of elimination was oxidation to HEAA, which is rapidly cleared in the urine 47% of the dose was excreted as HEAA during exposure and excretion was complete within 8 h of the end. The excretion half-life of HEAA was 2.7 h and its renal clearance was 121 mL/min, which indicates clearance by glomerular filtration, as creatinine clearance in these subjects was 124 mL/min. Renal clearance of 1,4-dioxane was 0.34 mL/min, compared with its metabolic clearance of 75 mL/min. 

DMPS and DMSA are derivatives of BAL, but they have been found to be more effective than BAL in experimental studies. Although still considered an investigational drug, DMPS decreased the mercury excretion half-life from 33.1 to 11.2 days in 2 workers exposed to high levels of mercury vapor (ATSDR 1992). In a study of the influence of DMPS and DMSA on renal deposition of mercury in rats, both... 

Johansson E, Halidin MM (1989) Urinary excretion half-life of delta 1-tetrahydrocannabinol -7-oic acid in heavy marijuana users after smoking. J Anal Toxicol 13 218-223... 

The skin absorption half-life of atrazine at 0.25 mg/kg dose was 39 hours for males and 43 hours for females. Another value of interest for monitoring worker dermal exposure is the urinary excretion half-life (See Table VII). 

The detoxification of nicotine in humans takes place mainly in the liver. The elimination half-life of the unaltered compound in blood plasma lies at around 2 hours, though its terminal excretion half-life in urine averages 11 hours. Nicotine is oxidised mainly (70-80 %) to cotinine, but also about 4 % to (l S,2 S)- and (Ti ,2 S)-nicotine ]SF-oxide. Cotinine, with an elimation half-life of up to 20 hours, is further hydroxylated in the 3 -position. Nicotine, cotinine and 3 -hydroxycoti-nine are excreted in the urine largely as glucuronic acid conjugates. [544]... 

Various adult studies Metabolic or isotopic label studies in adult volunteers Long-term retention = 25% of absorbed Pb short-term Pb excretion 50—60% of absorbed fraction excretion half-life 19 days Chamberlain et al. (1978), U.S. EPA(1986, Ch. 10)... 

Huestis, M. A., and E. J. Cone. 1998. Urinary excretion half-life of 1 l-nor-9-carboxy-delta9-tetrahydrocannabinol in humans. Therapeut. DrugMonit. 20 570-576. 

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