Excretion in Urine and Feces

Urinary excretion of bile salts by healthy subjects is apparently very limited. The urine contained 2 % of the radioactivity administered orally as i C-cholic acid to a healthy subject in whom 100% of the radioactivity was recovered (80) and 0.12% of radioactivity administered to four normal subjects when i C-cholate was given intravenously (25). Conventional methods do not detect bile salts in the urine of healthy subjects (81,82). In jaundice patients, however, bile salts are excreted in the urine regularly (83). The highest 24-hr excretion rates reported by Gregg occurred in patients with common bile duct obstruction (58 mg/24 hr) and drug-induced cholestasis (40 mg/24 hr). The cholate/chenodeoxycholate ratio was greater than 0.59 

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Radiocerium absorbed into the systemic circulation will be transported by blood proteins and be deposited predominantly in liver and bone. Deposition fractions will be about 0.45 for liver, 0.35 for bone, and 0.1 for other soft tissues with the remainder excreted in urine and feces. The retention times in liver and bone are long compared to the radioactive half-lives of the cerium isotopes. Therefore, their effective biological half-times in these organs will be approximately equal to their physical half-lives. Experimental data on internal organ distri-... 

Table 16— Uptake of various lanthanide and actinide preparations in liver and skeleton at l and 24 hours and excretion in urine and feces at 3 or 4 hours after intravenous injection in female rats...

To date, very little quantitative data exist regarding the toxicokinetics of endrin and its metabolites. Limited data were found regarding the absorption, distribution, metabolism, and excretion of endrin in humans and animals after inhalation, oral, or dermal exposure, which is especially relevant to occupational exposure scenarios. Endrin appears to be well absorbed orally, and distribution is primarily to fat and skin. Endrin is excreted in urine and feces, and the major biotransformation product is anti-12-hydroxy-... 

The metabolism of 1,1,1,2-tetrachloroethane (11.26), a representative aliphatic chlorohydrocarbon, provides an example of mechanistic ambiguity. When administered to mice, ca. 40-45% of the dose was excreted unchanged in the expired air, whereas ca. 30% and 4% of the dose was excreted in urine and feces as 2,2,2-trichloroethanol and 2,2,2-trichloroacetic acid, respectively [59]. Both Pathways a and b in Fig. 11.3, together with the redox reactions shown in Fig. 11.3, c, can explain these results. 

Excretion - 84% of total radioactivity is excreted in urine and approximately 4% in feces, resulting in a mean recovery of 88%. Less than 0.1 % of the dose was excreted in urine and feces as the parent compound. Elimination was essentially complete by 96 hours postdose. 

Metabolism/Excretion- Mitoxantrone is excreted in urine and feces as either unchanged drug or as inactive metabolites. 

All of these metabolites possess retinoid activity that is in some in vitro models more than that of the parent isotretinoin. However, the clinical significance of these models is unknown. After multiple oral dose administration of isotretinoin to adult cystic acne patients (18 years of age and older), the exposure of patients to 4-oxo-isotretinoin at steady state under fasted and fed conditions was approximately 3.4 times higher than that of isotretinoin. In vitro studies indicated that the primary P450 isoforms involved in isotretinoin metabolism are 2C8, 2C9, 3A4, and 2B6. Isotretinoin and its metabolites are further metabolized into conjugates, which are then excreted in urine and feces. 

Pharmacokinetics Rapidly, well absorbed from the GI tract. Protei n bi ndi ng 90%. Metabolized in liver. Excreted in urine and feces. Half-life 8 hr. 

Pharmacohinetics Absorbed rapidly and almost completely. Distributed rapidly and extensively. Crosses the blood-brain barrier. Protein binding 95%. Metabolized in the liver. Excreted in urine and feces. Half4ife 8 hr. 

Mechanism of Action An antiretroviral that is rapidly converted to amprenavir, which inhibits HIV-1 protease by binding to the enzyme s active site, thus preventingthe processing of viral precursors and resulting in the formation of immature, noninfectious viral particles. Therapeutic Effect Impairs HIV replication and proliferation. Pharmacokinetics Rapidly absorbed after PO administration. Protein binding 90%. Metabolized in the liver. Excreted in urine and feces. Half-life 7.7 hr. 

Mechanism of Action An alpha-adrenergic agonist that stimulates alphaj-adrenergic receptors. Inhibits sympatheticcardioaccelerat or and vasoconstrictor center to heart, kidneys, peripheral vasculature. Therapeutic Effect Decreases systolic, diastolic blood pressure (BP). Chronic use decreases peripheral vascular resistance. Pharmacohinetics Well absorbed from gastrointestinal (GI) tract. Widely distributed. Protein binding 90%. Metabolized in liver. Excreted in urine and feces. Not removed by hemodialysis. Half-life 6 hr. 

Pharmacokinetics Minimal absorption after topical administration. Minimal excretion in urine and feces. 

They undergo minimal or no metabolism and they are excreted in urine and feces either unchanged or in a microbiologically inactive form. Although there have been differences among individual tetracyclines as to their urinary and fecal excretion, these differences are not substantial. Tetracyclines are also eliminated in milk (233), attaining approximately 50-60% of the plasma concen-... 

Pharmacokinetic studies revealed rapid systemic absorption after intramuscular administration of dexamethasone, with peak plasma levels attained at 0.5 h and 6 h in dogs and rats, respectively. It is rapidly excreted in urine and feces. Its biotransformation profile is comparable in rats and humans and mainly involves hydroxylation to 6-hydroxy- and 2-dihydroxy-derivatives followed by conjuga-... 

Lee et al. (1975) measured urinary and fecal elimination of 32P in rats after oral administration of labeled white phosphorus. The total radioactivity excreted in urine and feces was assessed in three different groups of rats sacrificed at 4 hours or 1 or 5 days after dosing. Total excretion of 32P was far higher via the urinary route by 4 hours postdosing. Excretion of 32P via the fecal route increased rapidly between 4 hours and 5 days post-dosing. By 5 days post-dosing, combined urinary and fecal excretion accounted for -80% of the administered dose of 32P. 

Pharmacokinetics Omeprazole and lansoprazole are enteric-coated to protect them from premature activation by gastric acid. After absorption in the duodenum, they are transported to the acid parietal cell canaliculus, where they are converted to active species. Metabolites of these agents are excreted in urine and feces. 

As an example for the numerous generated graphs, the time course of the mean radioactivity blood and plasma concentration values (incl. standard deviation) after intravenous and oral administration is given in the summary graph (Fig. 1). Additionally, the mean amounts of dose excreted in urine and feces depending on time after administration is given in the subsequent Fig. 2. 

Table 2 14C-HMR 1556. Excretion in urine and feces, cage washings and amount of radioactivity in blood of exsanguination and carcass after oral administration of approx. 10 mg/kg and intravenous administration of approx. 5 mg/kg body weight to male rats (% of administered radioactivity).

Animals. More than 90% excreted in urine and feces within 48 hr the major excreted metabolite was the O-desmethyl derivative. 

Animals. Almost completely biotransformed and rapidly excreted in urine and feces... 

Figure 2. Zinc intake and excretion, study 1. Dietary intake is indicated by the top of the bar. The length of the vertical bar represents total excretion in urine and feces. Balance is indicated by the bottom of the bar. When the bottom of the bar is above the zero line, the balance is positive. When the bottom of the bar is below the zero line, the balance is negative.

Due to slow absorption and metabolism, 80% of an oral chlordane dose is excreted in urine and feces. Chlordane has also been found in human breast milk. Excretion of orally administered chlordane is slow and can take days or weeks. In two accidental poisoning reports, the half-life of chlordane in blood serum of the patients was 88 and 21 days. 

Wastewater from pharmaceutical industries producing these therapeutics may allow introduction of these endocrine disruptors into the ecosystem if proper filtration is not employed. Moreover, the conjugated products excreted in urine and feces from individuals receiving these pharmaceuticals also can be introduced into the wastewater supply. There are few published results regarding bioaccumulation and biotransformation of estrogen-like pharmaceutics released into the ecosystem. 

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