Similar half-lives Subject

Metabolism/Excretion- In healthy subjects, the half-life of pramlintide is approximately 48 minutes. Pramlintide is metabolized primarily by the kidneys. Des-lys pramlintide (2-37 pramlintide), the primary metabolite, has a similar half-life and is biologically active both in vitro and in vivo in rats. AUC values are relatively constant with repeat dosing, indicating no bioaccumulation. 

The plasma half-life of prednisolone following the oral administration of prednisone to normal subjects ranges form 2.5 to 3.5 h (126, 130, 131). Similar half-life values for prednisolone were observed after oral prednisolone is administered (126, 132, 133, 134). Nugent et al (135) found after an intravenous dose of 1 mg/kg body weight of prednisolone (sodium succinate salt) an average half-life of 3.5 h. After an intravenous dose of 0.3 mg/kg prednisolone as phosphate the mean plasma... 

After single-dose i.v. administration, total body clearance appears two- to four-fold higher in cancer patients than in healthy subjects, although elimination half-life (3.3-5.7 h) was similar in both groups. 

In a study with human subjects, whose urine pH was controlled with sodium bicarbonate and ammonium chloride, it was found that 10-25% of the administered pseudoephedrine hydrochloride was metabolized to norpseudoephedrine and the elimination of pseudoephedrine and norpseudoephedrine was related to urine pH. As the urine pH increased, the serum half-life of pseudoephedrine and norpseudoephedrine increased.15 In another similar study it was found that a decrease... 

In elderly volunteers, the pharmacokinetic profile is similar to that in younger subjects. However, clearance is reduced from 541 ml/min to 421 ml/min and the half-life is increased from 3.2 to 5.0 h. 

Pharmacokinetics A mean elimination half-life of approximately 5 hours has been reported after intravenous doses of Roferon-A. Pharmacokinetic parameters are similar in healthy subjects and cancer patients after intramuscular doses. Dose-proportionate increases in serum levels occur with doses up to 198 MIU. The bioavailability of interferon alfa-2a after intramuscular administration is 80% to 83%, and its volume of distribution is 0.223 to 0.748 liter/kg. The total body clearance of interferon alfa-2a has been reported to range from 2.14 to 3.62ml/min per kg. 

This agent has a broad spectrum of activity encompassing several neurotransmitter systems. In this light, clozapine is similar to such phenothiazines as CPZ and thioridazine (519). It is also subject to a hepatic first-pass effect, which produces metabolites with low or unknown pharmacological activity. It has an elimination half-life ranging from 6 to 33 hours and a volume of distribution (V 5 l /kg) lower than most other antipsychotics. This last quality indicates less drug is sequestered in tissue sites. Plasma levels of the parent compound at or above 350 ng/mL may be associated with a better clinical response ( 66, 520). Plasma levels are lower in men than women, especially male smokers (329). 

Buspirone may be an effective anxiolytic in the elderly patient and less likely than BZDs to produce excessive sedation ( 352, 353, 354 and 355). Dizziness, however, may be a problem. Zolpidem or zaleplon, particularly in lower doses (i.e., 2.5 to 5.0 mg at bedtime) may be viable alternatives ( 356). The elimination half-life of these two agents is approximately 3 hours in the elderly. Although it has sleep-enhancing properties similar to BZD hypnotics, it is less likely to alter sleep architecture. Whereas antidepressants and b -blockers may be useful alternatives in younger patients, no data document their effectiveness for anxiety in elderly patients ( 307). Although antipsychotics may be helpful in reducing severe agitation, their side effect profile makes them unsuitable for use in subjective anxiety states ( 300, 307). 

Nalbuphine hydrochloride is structurally related to oxymorphone and naloxone. It is approximately equipotent with morphine. Nalbuphine is metabolised in the liver to inactive metabolites. The plasma terminal half-life is approximately 5 h. The onset of analgesia is within 2-3 min of intravenous administration and 15 min after intramuscular injection, and lasts 3-6 h with an adult dose of 10 mg. With equi-analgesic doses, similar degrees of respiratory depression to that of morphine occur up to a dose of approximately 0.45 mg-kg-1. With higher doses a ceiling effect occurs. Sedation, possibly mediated by K-receptor activation, occasionally occurs. The incidence of psychotomimetic side effects is lower than with pentazocine. The abuse potential is low, but is can cause withdrawal symptoms in opioid-dependent subjects. It has occasionally been used to reverse opioid-induced respiratory depression. 

In normal subjects, the terminal half-life of injected calcifediol is 23 days, whereas in anephric subjects it is 42 days. The half-life of 24,25(OH)2D is probably similar. Tracer studies with vitamin D have shown a rapid clearance from the blood. 

Vitamin D and its metabolites circulate in plasma tightly bound to a carrier protein, the vitamin D-binding protein. This -globulin binds 25(OH)D and 24,25(OH)2D with comparable high affinity and vitamin D and l,25(OH)2D with lower affinity. In normal subjects, the terminal half-life of injected calcifediol is 23 days, whereas in anephric subjects it is 42 days. The half-life of 24,25(OH)2D is probably similar. Tracer studies with vitamin D have shown a rapid clearance from the blood. The liver appears to be the principal organ for clearance. Excess vitamin D is stored in adipose tissue. The metabolic clearance of calcitriol in humans indicates a rapid turnover, with a... 

Phenanthridine, like other monoazaaromatics which fluoresce only weakly in nonpolar solvents, is subject to marked fluorescence activation by hydroxylic solvents. Recent studies have shown this to result from the effects of solvent on vibronic interactions between re,77 and 77,77 electronic states, and the effect of solvent changes on the phosphorescence half-life has been similarly explained.237 Measurements of fluorescence and, more especially, phosphorescence characteristics have been proposed as analytical methods for mixtures containing phenanthridines238, 239 and detailed studies of the emission spectra of phenanthridine,240, 241 its cation,241 9-methylphenanthri-dine,242 and phenanthridine-iV-oxide243 have been reported. A... 

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