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T R Kommuru

Publications and source records attributed to T R Kommuru.

6 recordsLinked to original sources
PubMed2001

Self-emulsifying drug delivery systems (SEDDS) of coenzyme Q10: formulation development and bioavailability assessment.

The goals of our investigations are to develop and characterize self-emulsifying drug delivery systems (SEDDS) of coenzyme Q10 (CoQ10), using polyglycolyzed glycerides (PGG) as emulsifiers and to evaluate their bioavailability in dogs. Solubility of CoQ10 was determined in various oils and surfactants. SEDDS consisted of oil, a surfactant and a cosurfactant. Four types of self-emulsifying formulations were prepared using two oils (Myvacet 9-45 and Captex-200), two emulsifiers (Labrafac CM-10 and Labrasol) and a cosurfactant (lauroglycol). In all the formulations, the level of CoQ10 was fixed at 5.66% w/w of the vehicle. The in vitro self-emulsification properties and droplet size analysis of these formulations upon their addition to water under mild agitation conditions were studied. Pseudo-ternary phase diagrams were constructed identifying the efficient self-emulsification region. From these studies, an optimized formulation was selected and its bioavailability was compared with a powder formulation in dogs. Medium chain oils and Myvacet 9-45 provided higher solubility than long chain oils. Efficient and better self-emulsification processes were observed for the systems containing Labrafac CM-10 than formulations containing Labrasol. Addition of a cosurfactant improved the spontaneity of self-emulsification. From these studies, an optimized formulation consisting of Myvacet 9-45 (40%), Labrasol (50%) and lauroglycol (10%) was selected for its bioavailability assessment. A two-fold increase in the bioavailability was observed for the self-emulsifying system compared to a powder formulation. SEDDS have improved the bioavailability of CoQ10 significantly. The data suggest the potential use of SEDDS to provide an efficient way of improving oral absorption of lipophilic drugs.

Animals↗
PubMed2000

Chirality and its implications in transdermal drug development.

Today more than 50% of marketed drugs are chiral. It has been well recognized that the stereochemistry of chiral drugs has a major influence on their pharmacological, pharmacokinetic, and toxicological actions. Studies on enantiomeric differences in the percutaneous permeation of chiral compounds have been actively pursued in recent years. Stratum corneum, the rate-limiting barrier in transdermal permeation, is made up of keratin and ceramide, which could potentially provide chiral environment. Transdermal delivery is often facilitated by the presence of penetration enhancers, which act primarily by altering the diffusion by disrupting the highly ordered membrane structure or by affecting the partitioning behavior of the diffusant molecules. Enantioselective permeation was observed with some chiral excipients including terpene enhancers. While studies on crystalline structures of pure enantiomers and racemates are helpful in understanding the basis for differentiation of physicochemical properties, prediction and control of permeability of enantiomers and racemates based on the physicochemical characteristics would be highly beneficial. The flux characteristics of enantiomers and racemates appear to be dependent upon their thermodynamic properties. Such analyses have a predictive value and are useful in the transdermal drug product development of chiral molecules. While the decision to market either an individual enantiomer or racemate lies strictly under the control of the sponsors, the guidance of the Food and Drug Administration is very helpful. This review presents an overview of the skin structure and transport and a concise review of enantioselective permeation with or without chiral enhancers. Regulatory perspectives on chiral drug product development are also discussed.

Administration, Cutaneous↗
PubMed1999

Effect of chiral enhancers on the permeability of optically active and racemic metoprolol across hairless mouse skin.

The stratum corneum, the rate-limiting barrier in transdermal drug delivery, is chiral in nature and enantiomers behave differently with respect to their transport across the skin, resulting in enantioselective permeation. The permeation characteristics of individual enantiomers of metoprolol free base (MB) were investigated using hairless mouse skin. The influence of chiral permeation enhancers, l-menthol and (+/-)-linalool, on the permeation of MB was also investigated. In the absence of enhancers, the permeation profiles of R- and S-MB from donor solutions containing either RS-MB or pure enantiomers are comparable (p < 0. 05). In presence of enhancers, l-menthol and (+/-)-linalool, the flux values were increased 2.4- to 3.0-fold, respectively, and the permeation profiles of R- and S-MB from donor solutions containing RS-MB are comparable (p < 0.05). However, when donor vehicle contains pure enantiomers, the permeation enhancing effect of l-menthol on S-MB was significantly higher (by 25%) than on R-MB (p < 0.05). Further, in presence of l-menthol, the flux of S-MB from donor solution containing pure S-MB was 35% higher than the flux of RS-MB from racemate. No such effect was seen with (+/-)-linalool. In all the investigations, no enantiomeric inversion was observed during the permeation process. The lag times were shorter in the case of l-menthol compared with (+/-)-linalool.

Administration, Cutaneous↗
PubMed1999

Stability and bioequivalence studies of two marketed formulations of coenzyme Q10 in beagle dogs.

Coenzyme Q10 (CoQ10), a highly lipophilic compound present in the inner mitochondrial membrane, is essential for production of cellular energy in the form of ATP. CoQ10 is used as an antioxidant and also in the treatment of various cardiovascular disorders. The relative bioavailabilities of powder filled capsule (I) and oil-based formulation (II) of CoQ10 were compared in beagle dogs in an open, randomized, multiple dose, cross-over design. Poor and slow absorption characteristics were observed for both the formulations. The AUC, Cmax, and Tmax for formulation I and II are comparable (p < 0.05) where the values for formulation I are 22.84 +/- 6.3 micrograms ml-1 h, 0.51 +/- 0.11 microgram/ml, and 6.1 +/- 2.0 h whereas the values for formulation II are 24.32 +/- 5.6 micrograms ml-1 h, 0.55 +/- 0.16 microgram/ml, and 6.6 +/- 2.3 h, respectively. Stability of CoQ10 at various temperature and humidity conditions and its photostability were studied. Various antioxidants were evaluated to determine the type and amount of antioxidant(s) required to improve the stability of CoQ10. Large extent of degradation was observed at 45 degrees C and 55 degrees C. The effect of humidity conditions on degradation was insignificant. Among the various antioxidants studied, mixture of ascorbic acid (5%) and EDTA (0.1%) offered better protection than phenolic antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), or propyl gallate (PG). Further, increasing concentrations of phenolic antioxidants (from 0.1 to 0.3%) accelerated the degradation.

Animals↗
PubMed1998

Racemate and enantiomers of ketoprofen: phase diagram, thermodynamic studies, skin permeability, and use of chiral permeation enhancers.

The role of intrinsic and extrinsic factors on transport of a chiral drug through the skin was studied. Ketoprofen (KP) was chosen as a model chiral drug. A possible relationship between the melting characteristics and the flux values of S- and RS-KP was investigated. The potential use of chiral enhancers, menthol and linalool, was also investigated. Thermal analyses were carried out for individual enantiomers and the racemate of KP. The melting temperature of each enantiomer was 22 degreesC lower than that of the racemic compound. Peak temperatures from the melting endotherms were plotted as a function of enantiomeric composition to give the binary phase diagram. The phase diagram suggested the presence of a racemic compound, and it was verified by calculations of the liquidus curve in the dystectic region using reported methods. Powder X-ray diffraction studies also confirmed that the racemate of KP is a racemic compound. The permeability of individual enantiomers and the racemate of KP through mice skin was determined in vitro using side-by-side diffusion cells. Transfer of R- and S-KP from aqueous solutions of both the racemate and pure enantiomer showed no significant differences in the rates of permeation, indicating that the rate of transfer of KP across the mice skin from these solutions was independent of the stereochemistry of the drug. No evidence of racemization during the transfer process was observed. The permeation-enhancing ratio of linalool was higher, but not significant, than that of l-menthol. The predicted ratio of enantiomer to racemate flux through the skin by the MTMT concept (1. 97) is in close agreement with the experimentally determined ratio (1.79) across mouse skin.

Acyclic Monoterpenes↗