Effect of Ashwagandha and Aloe vera pretreatment on intestinal transport of buspirone across rat intestine

The transport of buspirone across rat intestine (duodenum, jejunum, ileum and colon) was studied by using the non-everted sac method. Rats were pretreated with ashwagandha (Withania somnifera) and Aloe vera juice for 7 days. The rats were sacrificed by using anesthetic ether, the intestinal segments were isolated and used for the studies. The probe drug (buspirone) solution was placed in the isolated intestinal sac. Samples were collected at preset time points and replaced with fresh buffer. The drug content in the samples was estimated using high performance liquid chromatography method. Control experiments were also performed. The results reveal that there was a significant (p < 0.05) difference compared to control, in the transport of buspirone from the intestinal sacs which were pretreated with ashwagandha and Aloe vera juice. It suggests that both ashwagandha and Aloe vera might be acting by inhibiting the transporters and enzymes which are responsible for transport/metabolism of buspirone.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Design and Evaluation of a Novel Gas Formation-Based Multiple-Unit Gastro-Retentive Floating Drug Delivery System for Quetiapine Fumarate

Purpose: To develop a gastro-retentive formulation of quetiapine fumarate in the form of floating minitablets.Methods: The system consisted of core units prepared by direct  compression process, which were coated with three successive layers, namely, an inner seal coat, effervescent layer and an outer polymeric layer of polymethacrylates.Results: Mini-tablets coated with Eudragit RS 30D (5, 7.5 and 10%)  released . 85% of the drug after 12 h, while those coated with Eudragit RL 30D (5, 7.5 and 10%) released . 85% drug within the same period. Drug release kinetic studies showed that drug diffusion fitted best to zero order and Higuchi models, indicating that drug release was anomalous  non-Fickian transport. In vivo gastric residence time results indicate that the units remained in the stomach for about 6 h (n = 3). There was nosignificant change in dissolution profiles before and after storage at 40‹C and 75% RH for 6 months.Conclusion: The developed floating mini-tablets of quetiapine fumarate exhibit prolonged release for .12 h, and thus may improve bioavailability and minimize fluctuations in plasma drug concentrations. Keywords: Mini-tablets; Floating delivery system; Effervescence, Polymeric membrane, Controlled release, Quetiapine fumarat

The Liquisolid technique: an overview

A novel "Powder Solution Technology" involves absorption and adsorption efficiency which makes use of liquid medications, drug suspensions admixed with suitable carriers, coating materials and formulated into free flowing, dry looking, non adherent and compressible powder forms. Based upon a new mathematical model expression, improved flow characteristics and hardness of the formulation has been achieved by changing the proportion of Avicel ® PH 200 and Aerosil ® PH 200 from 50:1 ratio to 5:1 and in which the drug is dispersed in an almost molecularly state. Due to their significantly improved wetting properties a greater drug surface area is exposed to the dissolution media, resulting in an increased dissolution rate and bio availability. By using the Liquisolid technique, sustained drug delivery systems were developed for the water soluble drugs in which hydrophobic non-volatile solvents are used as vehicles.A nova "Tecnologia da Solução Sólida" envolve eficiência de absorção e de adsorção, faz uso de medicações líquidas, suspensões de fármacos e misturas com transportadores adequados, materiais de cobertura e é formulada em formas sólidas em fluxo livre, secas, não aderentes e compressíveis. Com base em novo modelo matemático, características aprimoradas de fluxo e dureza da formulação foram alcançadas modificando-se a proporção de Avicel ® PH 200 e Aerosil ® PH 200 de 50:1 para 5:1, na qual o fármaco é disperso quase que no estado molecular. Devido às propriedades de umidificação significativamente aprimoradas e à área do fármaco exposta ao meio de dissolução, que resulta na velocidade de dissolução, a biodisponibilidade foi aumentada. Utilizando a técnica Liquisólido, desenvolveram-se sistemas de liberação controlada de fármacos solúveis em água, nos quais solventes hidrofóbicos não voláteis foram usados como veículos

Numerical Study of Geometry and Rotation Dependence on the Flow in Labyrinth Seals

A computational study was conducted on the flow, both compressible and incompressible, in a labyrinth seal at various geometries and rotation rates. The computations were performed using the commercial software Fluent® which solves the k-ε model to predict the flow field in the seal. Various clearance-pitch ratios were used to study the effect of clearance on the flow. The aspect ratio, which is defined as the pitch-height ratio was varied to study the influence of the depth of the cavity on the flow as a whole. These studies span a range of Taylor's number that is defined accordingly, while fixing the Reynolds number at 1000. The effects of clearance, aspect ratio and rotational rates are studied using carry-over coefficient and discharge coefficient. It is observed that a secondary recirculation zone (SRZ) occurs inside a seal cavity at above certain Taylor's number. This significantly changes the flow field in the seal and the cavity which results an increases in pressure drop across the seal for a given flow boundary condition. This formation of SRZ's is more evident in incompressible flow and occur at prohibitively high rotational speeds in case of air (compressible flow). It is also observed that flow with teeth on rotor are characterized by SRZ's while it's not case with teeth on stator. A flow map which shows the onset and presence of SRZ's is shown. The ratio of tangential velocity of the shaft to the average of the swirl velocity in a cavity at various geometries of the cavities are presented. They seem to be decreasing with decreasing depth and follow a linear pattern with the aspect ratios of the cavity

Biphasic gastroretentive drug delivery system of acyclovir: formulation and in vitro evaluation

A biphasic gastroretentive drug delivery system of acyclovir consisted of loading dose tablet and floating multiple matrix tablets was prepared by direct compression process. The delivery system was designed by hydroxy propyl methyl cellulose as retardant polymer with an effervescent component to get the desired buoyant and sustained release characteristics. All formulations compile within the limits. The FTIR studies did not show any evidence of an interaction between acyclovir and polymers. Dissolution studies revealed biphasic drug release pattern, with loading dose released within 30 min and floating multiple matrix tablets provided zero order sustained release profile for 12 h. It is concluded that floating multiple matrix tablets designed were particularly suitable as gastro retentive drug delivery system with anomalous non-fickian diffusion mechanism. The stability studies showed no significant change in dissolution profiles (f2 value > 50).Colegio de Farmacéuticos de la Provincia de Buenos Aire

Priprava i evaluacija dvofazičnih plutajućih tableta fenoverina

A biphasic gastroretentive drug delivery system of fenoverine was developed to maintain constant plasma concentration. The delivery system consisted of a loading-dose tablet and a floating multiple matrix tablet prepared by the direct compression process. The drug release from biphasic GRDDS in 0.1 mol L1 HCl and SGF (enzyme free) was sustained over 12 h with buoyant properties. Stability studies showed no significant change in dissolution profiles (f2 value > 50). Based on the release kinetics, it can be concluded that the floating multiple matrix tablet containing HPMC was a particularly suitable gastroretentive drug delivery system with a zero-order release profile.U radu je opisan razvoj bifazičnog sustava za isporuku fenoverina s produljenim zadržavanjem u želucu radi održavanja konstantne koncentracije lijeka u plazmi. Sustav je dobiven metodom izravne kompresije, a sastoji se od tablete za inicijalno doziranje i matriksne tablete za plutanje. Oslobađanje lijeka iz bifazičnog GRDDS u 0,1 mol L1 HCl i SGF (bez enzima) bilo je produljeno više od 12 h, a sustav je pokazao plutajuća svojstva. Ispitivanja stabilnosti pokazala su da nema značajne promjene u profilu oslobađanja (f2 > 50). Na temelju kinetike oslobađanja može se zaključiti da su plutajuće višeslojne matriksne tablete s HPMC posebno pogodan sustav za isporuku fenoverina u želucu s kinetikom oslobađanja nultog reda

Priprava i in vitro vrednovanje bukoadhezivnih tableta karvedilola

Buccoadhesive tablets of carvedilol were prepared using HPMC K4M, HPMC K15M and Carbopol 934 as mucoadhesive polymers. Fifteen formulations were developed with varying concentrations of polymers. Formulations of the BC or BD series were composed of HPMC K4M or HPMC K15M in ratios of 1:1 to 1:5 whereas in the BE series Carbopol 934 was used (1:0.25 to 1:1.50). The formulations were tested for in vitro drug release, in vitro bioadhesion, moisture absorption and in vitro drug permeation through porcine buccal mucosa. Formulation BC3 showed maximum release of the drug (88.7 ± 0.4%) with the Higuchi model release profile and permeated 21.5 ± 2.9% of the drug (flux 8.35 ± 0.291 µg h1cm2) permeation coefficient 1.34 ± 0.05 cm h1) through porcine buccal membrane. BC3 formulation showed 1.62 ± 0.15 N of peak detachment force and 0.24 ± 0.11 mJ of work of adhesion. FTIR results showed no evidence of interaction between the drug and polymers. XRD study revealed that the drug is in crystalline form in the polymer matrix. The results indicate that suitable bioadhesive buccal tablets with desired permeability could be prepared.Varirajući koncentracije bukoadhezivnih polimera HPMC K4M, HPMC K15M i Carbopol 934 pripravljeno je 15 tableta karvedilola. Pripravci iz serije BC ili BD izrađeni su iz karvedilola i HPMC K4 M ili HPMC K 15M u omjerima 1:1, 1:2, 1:3, 1:4 i 1:5, a pripravci iz BE serije iz karvedilola i Carbopol 934 u omjerima 1:0.25, 1:0.50, 1:0.75, 1:1.00 i 1:1.50. In vitro je ispitivana brzina oslobađanja ljekovite tvari, bioadhezija, apsorpcija vlage i permeacija kroz bukalnu membranu svinje. Iz pripravka BC3 postignuto je maksimalno oslobađanje (88,7 + 0,4 %) koje je slijedilo Higuchijev model i maksimalna permeacija 21,5 + 2,9 % (fluks 8,35 ± 0,291 µg h-1 cm-2; permeacijski koeficijent 1,34 ± 0,05 cm h-1). Sila odvajanja za taj pripravak bila je 1,62 ± 0,15 N, a adhezija 0,24 ± 0,11 mJ. FTIR ispitivanja su pokazala da nije bilo interakcija između ljekovite tvari i polimera, a XRD ispitivanja da je ljekovita tvar u kristaliničnoj formi u polimernom matriksu. Pripravljene bukalne tablete su dovoljno bioadhezivne, a permeacija iz njih je zadovoljavajuća

Formulation and evaluation of multilayered matrix tablets of diltiazem hydrochloride

In the present study matrix and multilayered matrix tablets of diltiazem HCl were formulated by using guar gum as matrix core component and cellulose derivative, Sodium Carboxy Methyl Cellulose (SCMC) as barrier layers. Marked difference in dissolution characteristics of D3 and D3L3 was observed and showed a statistically significant difference. The study revealed that the matrix tablets prolonged the release, but predominantly in a first order fashion. Layering with SCMC granules on the matrix core, provided linear drug release with zero order kinetics. Mean dissolution time for D3 and D3L3 were found to be 4.17 h and 16.45 h, while dissolution efficiency decreased, indicating slower drug release. In vivo transit time of the formulation D3L3 shows that it crossed the small intestine at 6 h and retained for longer time in colon at 12 h. FT-IR and DSC studies show there is no drug-excipeints interaction. Stability studies portray that no change either in physical manifestation or in dissolution profile after storage at 40 ± 2 °C/RH 75 ± 5 % for 3 and 6 months.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Optimization, Characterisation and Pharmacokinetic Studies of Mucoadhesive Oral Multiple Unit Systems of Ornidazole

The objective of the present study was to investigate the applicability of matrix type mucoadhesive oral multiple unit systems (MUS) for sustaining the release of ornidazole in the gastrointestinal tract (GIT). The MUS were prepared by ionotropic gelation method using chitosan and hydroxypropyl methyl cellulose K4M (HPMC K4M) according to 32 factorial designs and were evaluated in vitro and in vivo. The particle size length ranged from 0.78 to 1.30 mm and breadth from 0.76 to 1.30 mm, respectively. The entrapment efficiency was in range of 80 to 96%. The rapid wash-off test was observed faster at intestinal pH 6.8 as compared to acidic pH 1.2. The fluoroscopic study revealed the retention of MUS in GIT for more than 5 hours. The pharmacokinetic parameters Cmax, Tmax, mean residence time (MRT) and area under curve (AUC) of developed MUS were found to be improved significantly (p<0.05) when compared with marketed immediate release tablets each containing 500 mg of drug. This study demonstrates that the MUS could be a good alternative to immediate release tablets to deliver ornidazole and expected to be less irritant to gastric and intestinal mucosa