Tracking of crystalline-amorphous transition of carvedilol in rotary spun microfibers and their formulation to orodispersible tablets for in vitro dissolution enhancement.

Physicochemical characterization of microfibers including powder X-ray diffraction, differential scanning calorimetry, attenuated total reflectance Fourier transform infrared spectroscopy, and positron annihilation spectroscopy were used to track the crystalline-amorphous transition of carvedilol during formulation and stability testing. The applied methods unanimously indicated the amorphous transition of carvedilol in the course of rotary spinning, furthermore a supramolecular ordering of chains of polymer matrix was revealed out by positron annihilation spectroscopy. The accelerated stability study (40±2°C/75±5% RH, for 4 weeks) indicated a large stress tolerance capacity of fibers, since only a partial crystallization of the active compound was observable at the last sampling point. To demonstrate possible utilization of microfibers, orodispersible tablets containing 10mg of carvedilol were successfully prepared by direct compression applying common tableting excipients. All of the investigated tablet parameters (hardness, friability, in vitro disintegration time) complied with the pharmacopoeial requirements. The performed dissolution (pH 1.0 and 6.8) study indicated that the drug dissolution from the microfiber based formula was rapid, complete and independent from the pH of the applied media, while the dissolution from the control tablets, containing crystalline carvedilol was incomplete and was strongly influenced by the pH of the applied media.

Novel analogs of D-e-MAPP and B13. Part 1: synthesis and evaluation as potential anticancer agents.

A series of novel isosteric analogs of the ceramidase inhibitors, (1S,2R)-N-myristoylamino-phenylpropanol-1 (d-e-MAPP) and (1R,2R)-N-myristoylamino-4'-nitro-phenylpropandiol-1,3 (B13), with modified targeting and physicochemical properties were designed, synthesized, and evaluated as potential anticancer agents. When MCF7 cells were treated with the analogs, results indicated that the new analogs were of equal or greater potency compared to the parent compounds. Their activity was predominantly defined by the nature of the modification of the N-acyl hydrophobic interfaces: N-acyl analogs (class A), urea analogs (class B), N-alkyl analogs (class C, lysosomotropic agents), and omega-cationic-N-acyl analogs (class D, mitochondriotropic agents). The most potent compounds belonged to either class D, the aromatic ceramidoids, or to class C, the aromatic N-alkylaminoalcohols. Representative analogs selected from this study were also evaluated by the National Cancer Institute In Vitro Anticancer Drug Discovery Screen. Again, results showed a similar class-dependent activity. In general, the active analogs were non-selectively broad spectrum and had promising activity against all cancer cell lines. However, some active analogs of the d-e-MAPP family were selective against different types of cancer. Compounds LCL85, LCL120, LCL385, LCL284, and LCL204 were identified to be promising lead compounds for therapeutic development.

Novel analogs of D-e-MAPP and B13. Part 2: signature effects on bioactive sphingolipids.

Novel isosteric analogs of the ceramidase inhibitors (1S,2R)-N-myristoylamino-phenylpropanol-1 (d-e-MAPP) and (1R,2R)-N-myristoylamino-4'-nitro-phenylpropandiol-1,3 (B13) with modified targeting and physicochemical properties were developed and evaluated for their effects on endogenous bioactive sphingolipids: ceramide, sphingosine, and sphingosine 1-phosphate (Cer, Sph, and S1P) in MCF7 cells as determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Time- and dose-response studies on the effects of these compounds on Cer species and Sph levels, combined with structure-activity relationship (SAR) data, revealed 4 distinct classes of analogs which were predominantly defined by modifications of the N-acyl-hydrophobic interfaces: N-acyl-analogs (class A), urea-analogs (class B), N-alkyl-analogs (class C), and omega-cationic-N-acyl analogs (class D). Signature patterns recognized for two of the classes correspond to the cellular compartment of action of the new analogs, with class D acting as mitochondriotropic agents and class C compounds acting as lysosomotropic agents. The neutral agents, classes A and B, do not have this compartmental preference. Moreover, we observed a close correlation between the selective increase of C(16)-, C(14)-, and C(18)-Cers and inhibitory effects on MCF7 cell growth. The results are discussed in the context of compartmentally targeted regulators of Sph, Cer species, and S1P in cancer cell death, emphasizing the role of C(16)-Cer. These novel analogs should be useful in cell-based studies as specific regulators of Cer-Sph-S1P inter-metabolism, in vitro enzymatic studies, and for therapeutic development.

[New anti-arrhythmia agents]. / Neue Antiarrhythmika.

Use of class-I antiarrhythmic agents (encainide, flecainide or moricizine) to suppress asymptomatic ventricular premature depolarizations does not decrease, but rather increases mortality from cardiac events after myocardial infarction. These patients should not be treated with antiarrhythmic drugs until improved survival is shown in a controlled clinical trial. In other clinical conditions such as symptomatic tachyarrhythmias class-I agents should only be used if the expected benefit outweighs the risk of an adverse cardiac effect. The development of new class-I drugs does not seem promising. Esmolol is the first intravenous and ultrashort-acting beta-adrenoceptor blocker that can be used to treat supraventricular arrhythmias in the critical care setting; in addition, it displays high cardioselectivity. Specific class-III antiarrhythmic agents including sematilide and dofetilide have been shown to be effective against ventricular tachyarrythmias in preclinical studies, but their clinical value remains to be established. Torsades de pointes arrhythmia is an undesirable side-effect closely coupled to specific class-III action that may limit their future use. The known pharmacological profiles and limited controlled clinical studies make amiodarone and sotalol promising candidates for drugs that may improve survival of patients at risk for sudden cardiac death.