Profiles, pharmacokinetic

In cases of all but intravenous adininistration, dosage forms must make the active moiety available for absorption, ie, for dmg release. This influences the bioavailabiUty and the dmg s pharmacokinetic profile. Ideally the dmg is made available to the blood for distribution and elimination at a rate equal to those processes. Through technological developments dmg product design can achieve release, absorption, and elimination rates resulting in durations of activity of 8—12 hours, ie, prolonged action/controlled release dmg products (21,22). Such products improve the compliance rate of dmg usage by patients. 

Asoc inol. Asocainol, a diben2azonine derivative, has sodium channel (Class I) and calcium channel (Class IV) blocking activity that accounts for the antiarrhythmic activity. Preliminary studies indicate that the compound is effective against ventricular arrhythmias (88). Additional studies are needed to estabUsh efficacy, toxicological potential, and pharmacokinetic profile. 

Studies of the pharmacokinetics of this deHvery system in two animal models have been reported in the Hterature. After iajection of these microspheres at three doses, leuproHde concentrations were sustained for over four weeks foUowing an initial burst (116). The results iadicated that linear pharmacokinetic profiles in absorption, distribution, metaboHsm, and excretion were achieved at doses of 3 to 15 mg/kg using the dmg loaded microspheres in once-a-month repeated injections. 

The separation of enantiomers is a very important topic to the pharmaceutical industry. It is well recognized that the biological activities and bioavailabilities of enantiomers often differ [1]. To further complicate matters, the pharmacokinetic profile of the racemate is often not just the sum of the profiles of the individual enantiomers. In many cases, one enantiomer has the desired pharmacological activity, whereas the other enantiomer may be responsible for undesirable side-effects. What often gets lost however is the fact that, in some cases, one enantiomer may be inert and, in many cases, both enantiomers may have therapeutic value, though not for the same disease state. It is also possible for one enantiomer to mediate the harmful effects of the other enantiomer. For instance, in the case of indacrinone, one enantiomer is a diuretic but causes uric acid retention, whereas the other enantiomer causes uric acid elimination. Thus, administration of a mixture of enantiomers, although not necessarily racemic, may have therapeutic value. 

FIGURE 8.20 Drugs as subsets of clinical profiles. While burimamide, cimetidine, and metiamide are all active histamine H2 antagonists with ulcer healing activity burimamide lacks a suitable toxicity and pharmacokinetic profile and cimetidine is adequately absorbed but still toxic. Only metiamide fulfills the requirements of a clinically useful drug. 

Over 4 decades, between 1960 and 2000, the development of new antibiotics used well characterized basic structures for partial synthetic modifications, primarily to overcome resistance by increasing the pharmacodynamic properties and, secondarily, to improve the pharmacokinetic profile of older compounds. However, bacteria rapidly responded by acquiring additional genetic alterations either as mutations or by accumulating resistance genes as part of mobile genetic elements ( integrons) on transferable resistance plasmids. 

Interactions resulting from a change in the amount of diug reaching the site of action are called pharmacokinetic interactions (Fig. 1). A co-administered diug can affect any of the processes of absorption, distribution, metabolism, and excretion of the original diug, which are determinants of its pharmacokinetic profile [1-3]. 

Population pharmacokinetics is the application of pharmacokinetic and statistical methods to sparse data to derive a pharmacokinetic profile of central tendency. 

The potent activity of D-DOT against AZT- and 3TC-resistant HIV-1 strains together with its excellent pharmacokinetic profile in rhesus monkeys suggest that further development of D-DOT towards HIV-1 chemotherapy is warranted (Asif et al. 2007). 

Unity resulted in 4234 hits. After application of several filters and clustering of the remaining 1975 molecules, compounds from 18 of the 27 clusters were screened in Xenopus oocytes. One compound with an IC50 of 5.6pM belonged to a new class of Kvl.5 blockers and exhibited a favorable pharmacokinetic profile. After further optimization, compound 73 (IC50 = 0.7pM Fig. 16.9) resulted, with good oral bioavailability in rats [145]. 

Distribution is an important aspect of a drug s pharmacokinetic profile. The structural and physiochemical properties of a drug determine the extent of... 

Importantly, the currently available transporter models only cover a small fraction of all transporters involved in drug disposition. Other than incorporating current stand-alone transporter models into systemic models to directly predict drug pharmacokinetic properties, continued efforts are still needed to investigate other transporters such as MRP, BCRP, NTCP, and OAT, to get a more complete understanding of the drug pharmacokinetic profile. 

As discussed above, all ADMET aspects are dependent on each other and should all be considered when making predictions. Integrated analysis of different aspects of drug pharmacokinetic profiles is yet another future trend. Ultimately, drug ADMET properties should be predicted based on an integration of a compilation of in silico models reflecting different aspects of the process. 

The metabolic and pharmacokinetic profile of sucralose (this is a novel intense sweetener with a potency about 600 times that of sucrose) in human volunteers was studied by Roberts and coworkers [82]. Part of this study was realized using PLC in the following chromatographic system in which the stationary phase was silica gel and the mobile phase was ethyl acetate-methanol-water-concentrated ammonia (60 20 10 2, v/v). Separated substances were scraped off separately, suspended in methanol, and analyzed by filtration, scintillation counting, or enzymatic assay. It was shown that the characteristics of sucralose include poor absorption, rapid elimination, limited conjugative metabolism of the fraction absorbed, and lack of bio-accumulative potential. 

Avdeef A. HT solubility and permeability MAD-PAMPA analysis. In Pharmacokinetic Profiling in Drug Research, Testa, B., Kramer, S. D., Wunderli-Allenspach, H., Eolkers, G. 

P. A. Experimental and virtual physicochemical and pharmacokinetic profiling of new chemical entities. 

---