Time absorption

The actual time required for poly-L-lactide implants to be completely absorbed is relatively long, and depends on polymer purity, processing conditions, implant site, and physical dimensions of the implant. For instance, 50—90 mg samples of radiolabeled poly-DL-lactide implanted in the abdominal walls of rats had an absorption time of 1.5 years with metaboHsm resulting primarily from respiratory excretion (24). In contrast, pure poly-L-lactide bone plates attached to sheep femora showed mechanical deterioration, but Httie evidence of significant mass loss even after four years (25). 

Similar to pure polyglycoHc acid and pure polylactic acid, the 90 10 glycolide lactide copolymer is also weakened by gamma irradiation. The normal in vivo absorption time of about 70 days for fibrous material can be decreased to less than about 28 days by simple exposure to gamma radiation in excess of 50 kGy (5 Mrads) (35). 

When a single-dose intravenous and an oral (or other extravascular) plasma curve are both available from the same subject(s) one can define the mean absorption time MAT by means of the mean residence time obtained from the intravenous curve MRT, and the extravascular curve MRT ... 

This type of experiment allows quantification of the cream absorption time, as well as the evolution after saturation and returning to its original state. These... 

Best time to take doses At bedtime I m med iate- rel ease anytime during the day however, it is typically given at bedtime Extended-release anytime during the day After meals for best oral absorption On an empty stomach for best oral absorption if taken 30 minutes after a meal, as recommended by the manufacturer, peak absorption time is delayed, thereby further reducing the potential for hypotensive adverse effects20,24... 

Ammonium pyrrolidine dithiocarbamate (APDC) chelate coprecipitation coupled with flameless atomic absorption provides a simple and precise method for the determination of nanomol kg 1 levels of copper, nickel, and cadmium in seawater. With practice, the method is not overly time-consuming. It is reasonable to expect to complete sample concentration in less than 20 min, digestion in about 4 h, and sample preparation in another hour. Atomic absorption time should average about 5 min per element. Excellent results have been obtained on the distribution of nickel and cadmium in the ocean by this technique. 

Additionally, using the filling and absorption times established with the aid of electronics, the quantity of laundry or type of textile can be registered and the wash and rinse program can be modified as appropriate. The working principle as defined by water level in relation to process time is shown in the upper part of Fig. 3.6. 

Mean residence time, mean dissolution time, mean absorption time... 

Riegelman S, Collier P. The application of statistical moment theory to the evaluation of in vivo dissolution time and absorption time. J Pharmacokinet Biopharm 1980 8 509-534. 

Figure 10 Mean observed concentration-time profiles for the three extended-release formulations, fast ( ), medium (o), and slow ( ), whose in vitro dissolution data are shown in Figure 3 (panel a) and the derived mean absorption-time profiles (panel b).

Figure 11 Observed data (amount absorbed in vivo vs. amount released in vitro) for the three ER formulations whose dissolution data are shown in Figure 3 and absorption—time profiles in Figure 10. The fitted IVIVC equation is shown as well as the corresponding equation and predicted line. The dotted line represents a 1 1 relationship.

If the slopes of the absorption/time curves differ considerably, a positive hit is indicated (i.e., an enantioselective lipase-variant has been identified) (16). Figure 5 shows two typical experimental plots, illustrating the presence of a non-selective lipase (top) and a hit (bottom) (16). As a consequence of the crudeness of the test, quantitative evaluation is not possible. Therefore, the hits need to be investigated separately in laboratory-scale reactions and evaluated quantitatively by conventional chiral GC. About 800 plots of this kind can easily be recorded per day. A total of 40 000 lipase-variants were generated by epPCR, saturation mutagenesis, cassette mutagenesis, and DNA shuffling and screened in the model reaction. 

Salicylic Acid Absorption. The apical 5 cm of the primary and two seminal roots from each of three plants were out into 1-cm segments to form an experimental unit (ca. 0.08 g). Incubation solution cc ijjtalned 0.5 mM KCl, 0.25 mM CaSOjj, 0.5 mM salicylic acid, 10 nCl/mL [ C]-sallcyllc acid, with 25 mM Tris and 25 mM Mes buffers mixed to obtain pH 6.5. Because the salicylic acid was dissolved in absolute ethanol, the final concentration of ethanol in the incubation solution was 1 (v/v). Root segments were transferred to test tubes containing 10 mL continuously aerated incubation solution. After the predetermined absorption time, segments were collected from the incubation solution by rapid filtration on Whatman No. 2 filter paper. 

BZDs with rapid absorption produce a more rapid onset of clinical activity than those with slower absorption. BZDs given orally differ in their speed of absorption from the gastrointestinal tract. For example, absorption time is 0.5 hours for clorazepate, 1 hours for diazepam, 1.3 hours for triazolam, 2 hours for alprazolam and lorazepam, 2 to 3 hours for oxazepam, and 3.6 hours for flurazepam. Absorption, however, may be influenced by the presence or absence of food in the gastrointestinal tract. Thus, patients who take a BZD hypnotic with a bedtime snack may experience a slower onset of hypnotic activity than if the same drug were taken several hours after a meal. 

Testosterone, when administered by mouth, is rapidly absorbed. However, it is largely converted to inactive metabolites, and only about one sixth of the dose administered is available in active form. Testosterone can be administered parenterally, but it has a more prolonged absorption time and greater activity in the propionate, enanthate, undecanoate, or cypionate ester forms. These derivatives are hydrolyzed to release free testosterone at the site of injection. Testosterone derivatives alkylated at the 17 position, eg, methyltestosterone and fluoxymesterone, are active when given by mouth. 

Excitation-wavelength-dependent emission polarization studies indicate the presence of an overlapping xy polarized transition in the bluer part of the 290-315-nm range, as indicated in Fig. 5. The combination of static absorption, time-resolved emission, and emission quantum yield measurements suggests that the emitting state has the same polarization (z axis, linear), but is not the same state as that giving rise to the 362-nm absorption peak. These assignments for the 3.5-nm particles are summarized in Fig. 5. 

Mean Absorption Time The mean time required for drug to reach systemic circulation from the time of drug administration. This term commonly refers to the... 

Fig. 1. a) Normalized transient absorption time profiles for benzene ( ) in the gas phase (4 bar, T = 408 K) for = 1670 nm and kp,, = 275 nm. Also shown is a fit using the model described in the text (—). b) Normalized transient absorption time profiles for toluene ( ) in the gas phase (4 bar, T = 421 K) for = 1678 nm and = 280 nm. The solid line is a fit using the model described in the text. Residuals show the quality of the fits. The insets display the traces on a shorter timescale, the cross correlation of the experiment, and the comparison with the solution experiment in Fig. 3 (grey line). 

Fig. 2. Transient absorption time profiles of NKX-2311/ZnO at the probe wavelengths of 600, 700, 1050, 1150, 1300, and 2630 nm after 540 ran excitation by the femtosecond pulse with the intensity of about 10 pj. Thick solid lines are the result of a fitting procedure. Major time constants are indicated.

K is the matrix of molar absorptivity times pathlength, eh. A is the matrix of absoibance of the unknown. A matrix, such as A, with only one column or one row is called a vector. C is the vector of unknown concentrations. 

The effects of insulin are modified by various factors. The speed and extent of absorption of insulin depends, for example, on the site of injection (1), the depth of the subcutaneous injection, skin temperature (2), the presence of lipodystrophy, and variation in the extent of inactivation of injected insulin. The disposal of insulin depends on many factors. Exercise and hard work lower the blood glucose and thereby increase the effect of insulin. Infections and obesity reduce its effect. The timing of food intake and the composition of meals are also related to the action of insulin. A thin layer of fat, as sometimes occurs in the upper arm or in the thighs of thin men, can result in intramuscular injection, leading to faster absorption of long-acting insulins. This can reduce the absorption time by half (3). The major factors that affect the fate of injected insulin (and thereby also its risks) are listed in Table 1 (4). 

We can say that such a static device is a U( ) unipolar, set rotational axis, sampling device and the fast polarization (and rotation) modulated beam is a multipolar, multirotation axis, SU(2) beam. The reader may ask how many situations are there in which a sampling device, at set unvarying polarization, samples at a slower rate than the modulation rate of a radiated beam The answer is that there is an infinite number, because from the point of the view of the writer, nature is set up to be that way [26], For example, the period of modulation can be faster than the electronic or vibrational or dipole relaxation times of any atom or molecule. In other words, pulses or wavepackets (which, in temporal length, constitute the sampling of a continuous wave, continuously polarization and rotation modulated, but sampled only over a temporal length between arrival and departure time at the instantaneous polarization of the sampler of set polarization and rotation—in this case an electronic or vibrational state or dipole) have an internal modulation at a rate greater than that of the relaxation or absorption time of the electronic or vibrational state. 

In general, it is assumed that the oral absorption process follows Lrst-order kinetics. This assumption appears to be valid for majority of the drugs. The Lrst-order process can also satisfactorily describe the oral absorption process of some drugs with very poor water solubility. Sometimes, the inclusion of the absorption time lag may appear to be needed to account for the lag time for the dissolution of the drug substance from the dosage form into the aqueous media in the Gl tract. 

A number of patented technologies for multiparticulate dosage forms have been described recently, such as the Micropump system, which is an osmotically driven coated microparticle system designed to increase the absorption time for rapidly absorbed drugs.59 Combination of water-soluble and water-insoluble polymers could provide enhanced controlled release rates and profiles. A patented technology (COSRx) has been reported to be capable of delivering various sophisticated release profiles. The formulation involves a guar-gum-based tablet and a combination of water-soluble and water-insoluble polymeric tablet coat.60... 

Cmax- Observed maximum or peak concentration Single-dose crossover Parallel group Steady-state (optional) Rate metric (historical) Subject to inaccuracy due to discrete sampling Insensitive to absorption time course differences... 

MAT Mean absorption time Single-dose crossover Less sensitive to discrete sampling issues May mask absorption profile differences... 

Pharmacokinetic Measures of Systemic Exposure Both direct (e.g., rate constant, rate profile) and indirect (e.g., Cmax, Tmax, mean absorption time, mean residence time, Cmax normalized to AUC) pharmacokinetic measures are limited in their ability to assess rate of absorption. This guidance, therefore, recommends a change in focus from these direct or indirect measures of absorption rate to measures of systemic exposure. Cmax and AUC can continue to be used as measures for product quality BA and BE, but more in terms of their capacity to assess exposure than their capacity to reflect rate and extent of absorption. Reliance on systemic exposure measures should reflect comparable rate and extent of absorption, which in turn should achieve the underlying statutory and regulatory objective of ensuring comparable therapeutic effects. Exposure measures are defined relative to early, peak, and total portions of the plasma, serum, or blood concentration-time profile, as follows ... 

Figure 2.50. SPME absorption-time profile for four x-triazines and parathion using magnetic stirring. (Reprinted with permission from Ref. 139. Copyright 1997 Elsevier Science.)...

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