Release parameter

SY Choe, E Lipka, LX Yu, JR Crison, GL Amidon. Optimization of dosage form release parameters based on pharmacokinetic and gastrointestinal transit time considerations. Pharm Res 13 S292, 1996. 

Two kinds of general relationships can be established between the in vitro dissolution and in vivo bioavailability (1) IVIVC and (2) In vivo-in vitro associations. In the former, one or more in vivo parameters are correlated with one or more in vitro-release parameters of the product. In case of in vivo-in vitro associations, in vivo and in vitro performance of different formulations is in agreement, but a correlation does not exist per se. Situations can also exist where no correlation or association is possible between the in vitro and in vivo data (30). Regardless of which case applies, the extent of the relationships between the parameters must be clearly understood to arrive at a meaningful interpretation of the results (31). The procedures for comparing profiles and establishing an IVIVC are explained in detail in USP 27, Chapter < 1088 > and also addressed in Chapter 10 of this book. In the best case, IVIVC implies predictability of both similarity in and differences between in vitro and in vivo data in a... 

Figure 12 Simulation output for the slow formulation whose dissolution behavior is shown in Figure 3. Pharmacokinetic parameters F= 1, ka = 1000 hr-1, kw = 0.17 hr-1, V = 114L,/c0i = 1, tcol = 9 hr, ahs 96 hr. Dosing parameters dose = 10 mg, i = 24hr. IVIVC equation 4th order polynomial shown in Figure 11. Double Weibull (drug release) parameters Finf=102%, fi = 0.349, MDTa = 6.85 hr, 61 = 0.783, MDT2=18.7hr, and b2 = 2.11 (Table 2).

Figure 14. Effect of fission product recoil on release (parameter same as Fig. 11 except for thin high-diffusivity coating between kernel and outside coat)...

Discussion of excipient specifications and release parameters. Note any special requirements that are not typical compendial requirements (e.g., particle size). Include comparative evaluation for multiple sources. 

List of all applicable reports supporting the development of finished product specifications and release parameters (e.g., finished product specification justification report). 

Hence, a linear dependency of the HRRst from the external heat flux is expected (Figure 15.17) based on Schartel and Braun.55 The slope (referred to as the heat release parameter, HRP) is interpreted as a fire response parameter,60-108 whereas the intercept (HRR,) is considered a flammability parameter,62 107 at least on this length scale. 

Recently percolation theory is starting to be applied to the study of hydrophilic matrix systems. Figure 41 shows an example of the changes observed in several release parameters employed to estimate the critical point and the related percolation threshold in hydrophilic matrices prepared using KC1 as the model drug [73],... 

In hydrophilic matrices the drug threshold is less evident than the excipient threshold, which is responsible for the release control [73], In order to estimate the percolation threshold of HPMC K4M, different kinetic parameters were studied Higuchi rate constant, normalized Higuchi rate constant, and relaxation rate constant. The evolution of these release parameters has been studied as a function of the sum of the excipient volumetric percentage plus initial porosity. Recent studies of our research group have found the existence of a sample-spanning cluster of excipient plus pores in the hydrophilic matrix before the matrix is placed in contact with the liquid, clearly influences the release kinetics of the drug [73]. 

Models 103 and 104 generate release parameters of chemicals, such as the evaporation time estimated by the Chinn evaporation method, to run Model 105. These are characterized by two zones (as with the SCIES model) or Model 106, characterized by n zones, where n is up to four (such as for the MCCEM model). 

FIGURE 2.6. The dependence of the properties of Chapman-Jouguet waves upon the dimensionless heat-release parameter a, as determined by equations (31)-(34) with y = 1.3. 

In another study, Wu et al. from China used a neural network to model the formulation of salbutanol sulfate osmotic pump tablets, using the amount of hydroxypropyl methyl cellulose and polyethylene glycol present in the cellulose acetate coating, in addition to the coating weight, as control factors. Using the model, the authors predicted the release parameters for 1000 formulations, from which they selected an optimum with the desired release pattern. 

Out of the results of the intersection should follow an equilibrium concentration of 0.35 mg/m, which is not in accordance with the determined equilibrium value. So this experimental set up is a case of a situation which is not well defined and therefore not suitable for measurement of the relevant formaldehyde release parameters of the particleboard. 

The objective of this paper is to bring together original results on flavor release of soft cheese obtained over tiie last few years. First, results about the evolution of cheese taste during ripening are presented. The effect of the cheese matrbc on the evolution of taste-active compounds of the WSE are described. The second part deals with attempts to relate taste- and aroma release parameters with perception parameters in a range of cheeses. 

This part concerned attempts to relate taste- and aroma release parameters with perception parameters from a complex matrix such as soft cheeses. 

The challenge of our further studies is to elucidate matrix effect for bitterness and to try to relate salty and sour perception of soft cheeses with mineral and organic non volatile release parameters. 

Powers, W.l... J.l). liacr, and J. Skopp. 1992. Alternative soil water release parameters for distinguishing tillage effects. Soil Sci. Soc. Am.. 1. 56 873 878. 

Although liposomes are comprised of recognized non-toxic components, they cannot provide ideal storage or release parameters due to drug equilibrium inside and outside the vesicles. Solid microparticles and nanoparticles have been investigated as a means of overcoming this problem, and offer the possibility of building physically and chemically stable molecules. 

Numerical values of the parameters for Chapman-Jouguet waves are plotted in Figure 2.6 as functions of the dimensionless heat-release parameter a for y = 1.3. A representative value of a is a = 30, for which Figure 2.6 shows that, approximately, = 20, v+ = 0.58, = 12.5, and... 

Fig. 1. Time course of cell death parameters in tumor necrosis factor (TNF)-induced apoptosis. Human hepatoma cells (HepG2) were incubated in the presence of 400 nM actinomycin D plus 1.6 ng/ml recombinant human TNF (rhTNF)-a. MTT-dye reduction (parameter of mitochondrial function), lactate dehydrogenase (LDH) release (parameter for cell membrane rupture), and DNA fragmentation (parameter associated with typically apoptotic nuclear changes) were determined over a time period of 24 h. As is characteristic of apoptotic cell death, DNA fragmentation always preceded the other death parameters. Similar findings have been obtained in primary hepatocyte cultures and murine livers...

Fig. 9.22. Period versus latency relationship predicted by the one- and two-pool models based, respectively, on the IP3-sensitive and IPj-insensitive Ca -induced Ca release. Parameter values are those of figs. 9.21 and 9.19 (upper panel) for the one- and two-pool models, respectively (Dupont Goldbeter, 1993).

The last examples confirm that in the case of nearly phantom-like stress-strain relations additional information or assumptions ate necessary to obtain reliable results on the topological contributions from stress-strain measurements, because at present no microscopic theory of the constraint release parameter is available. 

Certain food and drug regulations regard all slow-release preparations as drugs and require their safety to be established prior to clinical application. Thus, a potassium ion-selective electrode has been employed to follow [416] the release parameters of 12 encapsulated potassium chloride tablets. Several of the tablets showed only medium dissolution rates for potassium and are unlikely to cause adverse effects such as gut ulceration. A sodium electrode has been similarly used to study the release of sodium phenobarbitone through a dialysis membrane into tris buffer [417]. Sodium in organic compounds has also been determined with an Orion 94-11 sodium electrode following combustion in a closed flask [418]. 

Fire propagation index (m/s )/(kW/m) / Heat release parameter AHcb/ Hg, kJ/kJ) Product generation parameter (y>j/AHg g/kJ) Thermal response parameter (kW s /m )... 

Net Heat of Complete Combustion (AHr) in MJ/kg Chemical Heat of Combustion (AHc/,) in MJ/kg Convective heat of combustion (AHcon) in MJ/kg Radiative heat of combustion (AHad) in MJ/kg Yield of a product yj) in kg/kg Heat release parameter (HRP)... 

The heat release rate is equal to the Heat Release Parameter (HRP) times the net heat flux [Eq. (53.22)]. Decrease in the HRP value would decrease the heat release rate. The HRP value can be decreased by decreasing the heat of combustion and/or increasing the heat of gasification by various chemical and physical means. An examination of the data in Table 53.9 for heat of combustion show that introduction of oxygen, nitrogen, sulfur, halogen, and other atoms into the chemical structures of the polymers reduces the heat of combustion. For example, the heat of combustion decreases when the hydrogen atoms attached to... 

---