Absorbed daily dose

Potential dermal exposure (PDE) was the sum of the amount of chlorpyrifos retained by the dosimeter (socks, gloves, and union suit) during the 20-min exposure period. Absorbed daily dose (ADD) was the sum of chlorpyrifos equivalents measured in urine for days 2,3, and 4. Home-use biomonitoring data are expressed as chlorpyrifos equivalents per day, as exposure continued throughout the test period. 

The WBDs retained an average potential dermal exposure (PDE) of 13,757 pg chlorpyrifos. If clothing penetration is assumed to be 10% and dermal absorption 9.6% per 24 hr, then the absorbed dose would be 132 pg, and the absorbed dosage would be about 1.9 pg/kg. Biological monitoring of the 13 volunteers wearing cotton dosimeters indicated that the absorbed daily dose that penetrated the WBD and was absorbed was 2 pg chlorpyrifos equivalents/kg (Table 2). 

When humans contact a chemical residue such as a pesticide on a treated surface, some of the deposit can be dislodged or transferred to skin or clothing. Ultimately, a portion of the amount transferred may be absorbed and constitute the absorbed daily dose (ADD). The ADD provides the most precise estimate of exposure that can be practically obtained for humans and has become the most useful expression of exposure for risk assessment and risk management. 

Average (absorbed) daily dose (ADD) Calculated dose rate averaged over a pathway-specific period of exposure expressed as a daily dose on a per-unit-body-weight basis. The ADD is used for exposure to chemicals with non-carcinogenic and non-chronic effects. This parameter is usually expressed in terms of mg/kg/d or other mass/mass/time nnits (USEPA, 1997c IRIS, 1999). 

The diet is the major route of human exposure to cadmium. Contamination of foods with cadmium results from its presence in soil and water. Concentrations of cadmium in foods range widely, and the highest average concentrations are found in mollusks, kidneys, livers, cereals, cocoa, and leafy vegetables. A daily intake of about 60 [tg would be required to reach a concentration of 50 mg/kg in the renal cortex of persons 50 years of age, assuming an absorption ratio of 5%. About 10% of the absorbed daily dose is rapidly excreted (WHO, 1989, 2001). 

An ideal" drug must be safe and effective. The mavimum daily dose should not exceed 200-300 mg. Drugs should be well absorbed orally and bioavailablc. Metabolic stability ensures a reasonable long half-life. Further on, a drug should be non-... 

Methadone is a p receptor agonist with special properties that make it particularly useful as a maintenance agent. Rehably absorbed orally, it does not reach peak concentration until about 4 hours after administration and maintains a large extravascular reservoir (Kreek 1979). These properties minimize acute euphoric effects. The reservoir results in a plasma half-life of 1—2 days, so there are usually no rapid blood level drops that could lead to withdrawal syndromes between daily doses. Effective blood levels are in the range of 200-500 ng/mL. Trough levels of 400 ng/mL are considered optimal (Payte and Khouri 1993). There is wide variability among individuals in blood levels with identical doses (Kreek 1979), and some have inadequate levels even with doses as high as 200 mg/day (Tennant 1987 Tenore 2003). 

The controlled-release (CR) formulation is more slowly absorbed and longer acting than immediate-release tablets. Patients need to increase the total daily dose by 30%, as it is not as bioavailable as the immediate-release levodopa/carbidopa. The CR formulation has a delayed onset (45 to 60 minutes) compared to the standard formulation (15 to 30 minutes). Thus, patients may also need to take immediate-release tablets or even a liquid formulation when they want a quicker onset of effect, such as with the first morning dose.1,8,25... 

When preparing an insulin infusion for a patient, several factors must be considered. Insulin will absorb to glass and plastic, reducing the amount of insulin actually delivered by 20% to 30%. Priming the tubing will decrease variability of insulin infused. Therefore, when patients can be converted safely from infusion to needle and syringe therapy, the total daily dose should be reduced by 20% to 50% of the daily infusion amount. 

Dosage formulation. Immediate-release formulations of terazosin and doxazosin are quickly absorbed and produce high peak plasma levels. Modified- or extended-release formulations of doxazosin, alfuzosin, and tamsulosin produce lower peak levels, but more sustained therapeutic plasma levels, than immediate-release formulations and have less potential for producing hypotensive episodes, thereby allowing initiation of treatment with a therapeutic dose and once daily dosing.25-27... 

When treating folic acid deficiency, an initial daily dose of 1 mg/day by mouth typically is effective. Absorption of folic acid generally is rapid and complete. However, patients with malabsorption syndromes may require larger doses (up to 5 mg/day). Similar to vitamin B12 deficiency, resolution of symptoms and reticulocytosis is prompt, occurring within days of commencing therapy. Hgb will start to rise after 2 weeks of therapy and may take from 2 to 4 months to resolve the deficiency completely. Afterwards, if the underlying deficiency is corrected, folic acid replacement can be discontinued. However, in cases where folic acid is consumed rapidly or absorbed poorly, chronic replacement may be required. 

Iron-deficiency anemia in chronic PN patients may be due to underlying clinical conditions and the lack of iron supplementation in PN. Parenteral iron therapy becomes necessary in iron-deficient patients who cannot absorb or tolerate oral iron. Parenteral iron should be used with caution owing to infusion-related adverse effects. A test dose of 25 mg of iron dextran should be administered first, and the patient should be monitored for adverse effects for at least 60 minutes. Intravenous iron dextran then may be added to lipid-free PN at a daily dose of 100 mg until the total iron dose is given. Iron dextran is not compatible with intravenous lipid emulsions at therapeutic doses and can cause oiling out of the emulsion. Other parenteral iron formulations (e.g., iron sucrose and ferric gluconate) have not been evaluated for compounding in PN and should not be added to PN formulations. 

Human intake of total mercury from the diet normally ranges between 7 and 16 pg daily (Schumacher et al. 1994 Richardson et al. 1995). Fish consumption accounts for much of this exposure in the form of methylmercury 27% of the intake, and 40% of the absorbed dose. Intake of inorganic mercury arises primarily from foods other than fish, and is estimated at 1.8 pg daily with 0.18 pg absorbed daily (Richardson etal. 1995). In certain areas of India, blood mercury concentrations of people who ate fish were three to four times higher than non-fish eaters (Srinivasen and Mahajan 1989). In some countries, mercury in dental amalgams accounts for 2.8 pg daily, equivalent to as much as 36% of the total mercury intake and 42% of the absorbed dose (USPHS... 

Pharmacokinetics Allopurinol is approximately 90% absorbed from the Gl tract. Effective xanthine oxidase inhibition is maintained over 24 hours with single daily doses. Allopurinol is cleared essentially by glomerular filtration oxipurinol is reabsorbed in the kidney tubules in a manner similar to the reabsorption of uric acid. 

Sparfloxacin - Sparfloxacin is well absorbed following oral administration. Steady-state concentration was achieved on the first day by giving a loading dose that was double the daily dose. Oral absorption of sparfloxacin is unaffected by administration with milk or food, including high-fat meals. Sparfloxacin distributed well into the body. It penetrates well into body fluids and tissues. Sparfloxacin is metabolized by the liver. It is excreted in the feces (50%) and urine (50%). 

The tricyclic antidepressants are all lipid-soluble, are well absorbed from the gut, and are widely distributed in the body. Peak plasma levels are reached 2-6 hours after a single oral dose and elimination half-life is between 8 hours and 36 hours, generally allowing once-daily dosing. Most have active metabolites, also with relatively long half-lives. They are highly bound to plasma proteins (75-95%) and undergo extensive hepatic metabolism. 

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