Thermally reversible in situ gelling carbamazepine liquid suppository

Carbamazepine (CBZ), indicated for the control of epilepsy, undergoes extensive hepatic first-pass elimination after oral administration. A rectal dosage form of CBZ is not commercially available, although it is of particular interest when oral administration is impossible. Conventional suppositories can cause patient discomfort and may reach the end of the colon; consequently, the drug can undergo the first-pass effect. Mucoadhesive liquid suppositories of CBZ were prepared by adding carbopol to formulation of thermally gelling suppositories that contain 20% poloxamer 407 and either 15% poloxamer 188 or 1% methylcellulose. Gellan gum was also tried instead of 20% poloxamer. All formulations contained 10% CBZ. The characteristics of the suppositories differed depending on the formulation. The formula containing 20% poloxamer 407, 1% methylcellulose, and 0.5% carbopol showed reasonable gelation temperature, gel strength and bioadhesive force. The analysis of release mechanism showed that CBZ released from the suppositories by Fickian diffusion. In vivo evaluation of the same formulation showed higher peak plasma concentration of CBZ compared with the orally administered suspension containing the equivalent amount of drug. However, there was no statistical significant difference (p > 0.05) in extent of bioavailability between the liquid suppository and oral suspension as indicated by the values of AUC(0 - infinity), 17.9 and 18.8 micro g x h/ml, respectively. These results suggested that mucoadhesive in situ gelling liquid suppository could be an effective and convenient delivery system of carbamazepine.     

Development of a poloxamer analogs/carbopol-based in situ gelling and mucoadhesive ophthalmic delivery system for puerarin

Conventional ophthalmic solutions often eliminate rapidly after administration and cannot provide and maintain an adequate concentration of the drug in the precorneal area. To solve these problems, we developed a thermosensitive in situ gelling and mucoadhesive ophthalmic drug delivery system containing puerarin based on poloxamer analogs (21% (w/v) poloxamer 407/5% (w/v) poloxamer 188) and carbopol (0.1% (w/v) or 0.2% (w/v) carbopol 1342P NF). The combined solutions would convert to firm gels under physiological condition and attach to the ocular mucosal surface for a relative long time. The incorporation of carbopol 1342P NF not only did not affect the pseudoplastic behavior with hysteresis of the poloxamer analogs solution and led to a higher shear stress at each shear rate, but also enhanced the mucoadhesive force significantly. In vitro release studies demonstrated diffusion-controlled release of puerarin from the combined solutions over a period of 8h. In vivo evaluation (the elimination of puerarin in tear and intraocular pressure-lowering effect) indicated the combined solutions had better ability to retain drug than poloxamer analogs or carbopol alone. It appears that ocular bioavailability can be increased more readily by using the in situ gelling and mucoadhesive vehicle.     

Thermally Reversible In Situ Gelling Carbamazepine Liquid Suppository

Carbamazepine (CBZ), indicated for the control of epilepsy, undergoes extensive hepatic first-pass elimination after oral administration. A rectal dosage form of CBZ is not commercially available, although it is of particular interest when oral administration is impossible. Conventional suppositories can cause patient discomfort and may reach the end of the colon; consequently, the drug can undergo the first-pass effect. Mucoadhesive liquid suppositories of CBZ were prepared by adding carbopol to formulation of thermally gelling suppositories that contain 20% poloxamer 407 and either 15% poloxamer 188 or 1% methylcellulose. Gellan gum was also tried instead of 20% poloxamer. All formulations contained 10% CBZ. The characteristics of the suppositories differed depending on the formulation. The formula containing 20% poloxamer 407, 1% methylcellulose, and 0.5% carbopol showed reasonable gelation temperature, gel strength and bioadhesive force. The analysis of release mechanism showed that CBZ released from the suppositories by Fickian diffusion. In vivo evaluation of the same formulation showed higher peak plasma concentration of CBZ compared with the orally administered suspension containing the equivalent amount of drug. However, there was no statistical significant difference (p > 0.05) in extent of bioavailability between the liquid suppository and oral suspension as indicated by the values of AUC_{0 - ∝}, 17.9 and 18.8 μ g.h/ml, respectively. These results suggested that mucoadhesive in situ gelling liquid suppository could be an effective and convenient delivery system of carbamazepine.     

Semisolid systems containing propolis for the treatment of periodontal disease: in vitro release kinetics, syringeability, rheological, textural, and mucoadhesive properties

Formulations containing poloxamer 407 (P407), carbopol 934P (C934P), and propolis extract (PE) were designed for the treatment of periodontal disease. Gelation temperature, in vitro drug release, rheology, hardness, compressibility, adhesiveness, mucoadhesion, and syringeability of formulations were determined. Propolis release from formulations was controlled by the phenomenon of relaxation of polymer chains. Formulations exhibited pseudoplastic flow and low degrees of thixotropy or rheopexy. In most samples, increasing the concentration of C934P content significantly increased storage modulus (G'), loss modulus (G'), and dynamic viscosity (eta'), at 5 degrees C, G' exceeded G'. At 25 and 37 degrees C, eta' of each formulation depended on the oscillatory frequency. Formulations showed thermoresponsive behavior, existing as a liquid at room temperature and gel at 34-37 degrees C. Increasing the C934P content or temperature significantly increased formulation hardness, compressibility, and adhesiveness. The greatest mucoadhesion was noted in the formulation containing 15% P407 (w/w) and 0.25% C934P (w/w). The work of syringeability values of all formulations were similar and very desirable with regard to ease of administration. The data obtained in these formulations indicate a potentially useful role in the treatment of periodontitis and suggest they are worthy of clinical evaluation.     

Effect of flavors on the viscosity and gelling point of aqueous poloxamer solution

This study examined the effects of flavors, which are usually added to improve the appeal of pharmaceutical agents, on the viscosity and gelling point of 18% (w/w) aqueous poloxamer 407 solutions. Monoterpenes, esters, alcohols, aldehyde . ketones and lactone type flavors were examined. The concentrations of flavor ranged from 0.1 to 1.0% (w/w). After adding a flavor to the aqueous poloxamer 407 solution, the viscosity of the solution was measured using a Brookfield viscometer, and the gelling point was determined from the viscosity vs. temperature plot. The gelling point of the aqueous poloxamer 407 solution decreased with increasing concentration of flavors except for coumarin, vanillin and ethylvanillin. Thermal analysis with DSC showed an interaction between the flavors and poloxamer 407. These results suggest that the flavors bind to the hydrophilic end chains of poloxamer 407, which increases the viscosity, causing gelation at lower temperatures.     

丙烯酸-泊洛沙姆407共聚物的合成及其原位胶凝性质

目的制备丙烯酸和泊洛沙姆407构成的共聚物,研究其温度敏感的原位胶凝性质。方法将泊洛沙姆407溶于丙烯酸单体,引发聚合反应,产物用红外光谱和凝胶渗透色谱表征。用旋转黏度计测定共聚物水溶液的黏度随温度的变化。以维生素B12为模型药物,研究药物的释放性质。结果较低浓度的丙烯酸泊洛沙姆407共聚物水溶液具有受热原位胶凝的性质,其胶凝特征与共聚物的组成、浓度、溶液pH等有关,共聚物凝胶可延缓药物释放。结论丙烯酸泊洛沙姆407共聚物可望应用于黏膜给药的原位凝胶递药系统。     

Thermosetting gel for the delivery of 5-aminolevulinic acid esters to the cervix

5-Aminolevulinic acid (5-ALA)-mediated photodynamic therapy has been proposed as an alternative, cervix-sparing treatment for cervical intraepithelial neoplasia (CIN). In this context, topical application of 5-ALA to the cervix is beneficial due to the small necessary dose and its minimal side effects. Therefore, lipophilic 5-ALA esters, such as hexylaminolevulinate (HAL), have led to improved local bioavailability and therapeutic efficacy. Hydrogels have shown to be more appropriate for the local delivery of these derivatives, but due to the limited long-term stability of such formulations at 25 degrees C, the development of an extemporaneously prepared hydrogel targeting CIN can be advantageous. Therefore, a poloxamer 407 thermosetting gel, which is liquid at room temperature and becomes a semi-solid when in contact with the female genital tract, has been evaluated in vitro and in vivo. Rheological evaluation has shown that a 17.0% poloxamer 407 hydrogel with a sol-gel transition at 24.8 +/- 0.6 degrees C was the best formulation for easy application and optimal residence time. Furthermore, similarly to other hydrogels previously tested, such a formulation shows a more complete HAL release in vitro than conventional cream vehicles, and tends to increase porphyrin accumulation in nude mice skin. Finally, in vitro release profiles were correlated to the in vivo results.     

New method for ophthalmic delivery of azithromycin by poloxamer/carbopol-based in situ gelling system

This study focused on preparation and evaluation of a thermosensitive and mucoadhesive in situ gelling ophthalmic system of azithromycin (ATM). Poloxamer 407 (P407) and poloxamer 188 (P188) were used as gelling agents. Addition of Carbopol 974P (CP 974P) to the gelling systems could increase the solubility of ATM by salt effect and enhance the mucoadhesive property of the systems. Gelation temperature of these systems ranged from 31.21–36.31°C depending on the ratio of P407 and P188. Mucoadhesion force of the system composed of P407/P188/CP 974P (21/5/0.3%, w/v) was 2.3-fold that without carbopol 974P. Viscosity of the formulation was in a suitable range at 25°C and pseudoplastic behavior was observed at 35°C. The formulation exhibited a 24-h sustained release of ATM. In vivo resident experiments showed AUC_0–12 of ATM in rabbit tears increased by 1.78-fold for in situ gel compared with eye drop. At 12?h, tear concentrations exceeded minimum inhibitory concentration (MIC) breakpoint for the most common causative pathogens of bacterial conjunctivitis by 2.8-fold. Results in vitro and in vivo indicated that this droppable gel performed better than ATM eye drop did.     

Formulation and preliminary in vivo dog studies of a novel drug delivery system for the treatment of periodontitis

A novel drug delivery system for the treatment of periodontitis was developed using two components. The first was tetracycline base loaded into the microtubular excipient halloysite, which was coated with chitosan to further retard drug release. Encapsulation efficiencies of 32.5% were achieved with the loading procedure, with tetracycline base showing in vitro release for up to 50 days in simulated gingival crevicular fluid. The second component developed was a vehicle for the drug loaded coated halloysite, which was primarily based on the thermoresponsive polymer, poloxamer 407. A concentration of 20% was chosen with the thermoresponsivity of the system modified using PEG 20,000 so that the mobile product at room temperature would gel by temperature rise following syringing into a periodontal pocket. Retention of the overall system in the pocket was further improved by the addition of octyl cyanoacrylate (OCA). The thermoresponsivity of the poloxamer 407 system proved to be sensitive to the presence of added excipients with the levels of PEG 20,000 and OCA requiring modification in the presence of the halloysite component. A final formulation was developed which consisted of 200 mg of halloysite double loaded with tetracycline base and coated with chitosan, suspended in 1 ml of poloxamer 407 20% (w/w), PEG 20,000 0.5% (w/w), OCA 1.0% (w/w), water to 100%, adjusted to pH 4. The syringeability of this formulation at various temperatures was evaluated to ensure ease of delivery to the periodontal pocket. A stability study was performed to examine the change in thermoresponsivity over time, with the final formulation found to be stable for at least 9 months when stored at room temperature (approximately 20 degrees C). This formulation offered ease of delivery to the periodontal pocket and sustained release of the antibiotic for up to 6 weeks. The formulation had preliminary in vivo testing performed in dogs to determine levels of drug release, antimicrobial activity and retentive ability of the product. A wound pocket creation model was developed for the purposes of the trial. The product was easy to deliver to the pockets with application times of less than 1 min. Results showed the product was retained in the pocket for up to 6 weeks with effective tetracycline levels released locally over this time period, which achieved good antibacterial activity.     

Thermosensitive and mucoadhesive in situ gel based on poloxamer as new carrier for rectal administration of nimesulide

Poloxamer 407 has excellent thermo-sensitive gelling properties. Nevertheless, these gels possess inadequate poor bioadhesiveness and high permeability to water, which limited its' application as a thermoresponsive matrix. The main aim of the present investigation was to develop thermosensitive and mucoadhesive rectal in situ gel of nimesulide (NM) by using mucoadhesive polymers such as sodium alginate (Alg-Na) and HPMC. These gels were prepared by addition of mucoadhesive polymers (0.5%) to the formulations of thermosensitive gelling solution containing poloxamer 407 (18%) and nimesulide (2.0%). Polyethylene glycol (PEG) was used to modify gelation temperature and drug release properties. The gelation temperature and drug release rate of the prepared in situ gels were evaluated. Gelation temperature was significantly increased with incorporation of nimesulide (2.0%) in the poloxamer solution, while the addition of the mucoadhesive polymers played a reverse role on gelation temperature. The addition of PEG polymers increased the gelation temperature and the drug release rate. Among the formulations examined, the poloxamer 407/nimesulide/sodium alginate/PEG 4000 (18/2.0/0.5/1.2%) exhibited the appropriate gelation temperature, acceptable drug release rate and rectal retention at the administration site. Furthermore, the micrographic results showed that in situ gel, given at the dose of 20mg/kg, was safe for no mucosa irritation. In addition, it resulted in significantly higher initial serum concentrations, C(max) and AUC of NM compared to the solid suppository.     

Effects on splenic, hepatic, hematological, and growth parameters following high-dose poloxamer 407 administration to rats

The nonionic surfactant poloxamer 407, NF (PIuronic ^® F-127, NF) has previously been shown to produce marked hyperlipidemia in rats at a dose of 1.5 g/kg for greater than 96 h following a single intraperitoneal (i.p.) injection (Wout et al. J. Parenter. Sci. Technol., 46 (1992) 192–200). In an effort to characterize any potential toxicity of the polymeric vehicle to various organ systems in the rat following multiple i.p. injections, a dose of 0.33 g/kg per day (10% w/w solution) or 1.0 g/kg per day (30% w/w solution) of poloxamer 407 was administered once daily for 4 consecutive days. When compared to control (non-injected) animals, rats injected with 0.33 g/kg per day of poloxamer 407 did not show a significant (p > 0.05) increase or decrease in spleen, liver, or total body weight. A complete blood count (CBC) with a white blood cell (WBC) differential was performed on blood samples collected on day five from rats injected with poloxamer 407 at both doses. The CBC with WBC differentia] was conducted to assess any changes in the WBC count, percent lymphocytes (LY), percent monocytes (MO), percent granulocytes (GR), red blood cell (RBC) count, hemoglobin (HGB), percent hematocrit (HCT), and the mean corpuscular volume (MCV) following administration of poloxamer 407. Rats injected i.p. with a dose of 0.33 g/kgper day of poloxamer 407 for 4 days demonstrated a significant (p < 0.05) increase in the number of MO when compared to controls. Administration of 1.0 g/kg per day of poloxamer 407 to rats for 4 days demonstrated distinct splenomegaly when compared to non-injected control animals. In addition, a significant (p < 0.05) reduction in body weight and significant (p < 0.05) decrease in the percent LY, RBCs, HGB, and percent HCT were noted. Lastly, a significant (p < 0.05) increase in the number of WBCs and the percent MO was observed in this same group of rats. However, rats administered 1.0 g/kg per day of poloxamer 407 for 4 days were observed to have no detectable changes in the values of the MCV, the percent GR, or liver-to-body weight ratio when compared to control animals. Thus, repetitive i.p. injections of poloxamer 407 to rats at a dose of 1.0 g/kg per day for four days results in splenomegaly and a reduction in total body weight. Splenomegaly in rats administered poloxamer 407 at a dose of 1.0 g/kg per day resulted from red pulp expansion due to infiltration of macrophages which contained phagocytized lipids.     

Biological activity of urease formulated in poloxamer 407 after intraperitoneal injection in the rat.

The advent of genetic engineering has resulted in a proliferation of protein pharmaceuticals available for a variety of therapeutic needs. However, the formulation and delivery of these proteins remain an intriguing challenge. Polymer-based protein drug delivery systems continue to be investigated, although many of the fabrication techniques used to incorporate proteins into the polymer matrix or device result in irreversible inactivation (denaturation) of the proteins. A well-characterized model enzyme, urease, was formulated in 33% (w/w) poloxamer 407 (Pluronic F-127) vehicle and injected intraperitoneally (ip) into rats in an attempt to achieve both preservation of biological activity and sustained release of the protein. The resulting ammonia concentration in plasma-time profiles were compared with those for rats injected with an identical dose (27.6 units of activity per 200 g of body weight) of urease dissolved in pH 7 phosphate buffer. Neither a pH 7 phosphate buffer solution nor poloxamer 407 (33%, w/w) dissolved in pH 7 phosphate buffer, when injected ip into rats, resulted in elevated ammonia levels in plasma. The time to reach a maximum ammonia level in plasma was increased approximately threefold following the injection of the urease-poloxamer 407 formulation, compared with that in control rats administered an identical dose of urease in solution. In addition, hyperammonemia was extended almost threefold in treated rats compared with control rats, without untoward effects. However, prolonged hyperammonemia in animals receiving an ip injection of the urease-poloxamer 407 formulation may have potentially resulted from the reduced clearance of ammonia and ammonium ion in the proximal tubules of the rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

安乃近原位凝胶的制备及体外评价

目的 制备安乃近原位凝胶,延长安乃近在体内的作用时间.方法 以泊洛沙姆407(P407)和泊洛沙姆188(P188)作为载体材料,采用冷溶法制备安乃近原位凝胶,考察P407和P188的含量、亚硫酸氢钠及安乃近浓度对胶凝温度的影响,并用透析袋法考察凝胶的体外释药情况.结果 当P407浓度为23％、P188浓度为6％、亚硫酸氢钠的浓度为0.2％时,所制得的安乃近原位凝胶注射剂的胶凝温度合适,为35.3℃时,该凝胶在1h内的平均体外累积释放率为40.57％,较安乃近水溶液同时间内的累积释放率低50.39％.结论 安乃近原位凝胶的温敏性明显,其胶凝温度适合体内给药;安乃近原位凝胶对安乃近药物的释放显示出了明显的缓释效应,可以进一步用于临床.     

Sustained Delivery of Interleukin-2 from a Poloxamer 407 Gel Matrix Following Intraperitoneal Injection in Mice

Parenteral delivery of recombinant biologic response modifiers (BRMs) remains a challenge because of the brief intravascular half-life of most recombinant proteins and their associated rapid clearance from the circulation. Recombinant derived interleukin-2 (rIL-2) was formulated with Pluronic F-127, N.F. (poloxamer 407, N.F.) and the biological activity determined vs time at 4, 22, and 37°C. As assessed by rIL-2-induced peripheral blood lymphocyte (PBL) uptake of [³H]thymidine, storage of rIL-2/poloxamer 407 (33% w/w) for 72 hr at 4 and 22°C did not result in an overall negative slope of the [³H]thymidine vs time profiles. However, storage of an rlL-2/poloxamer formulation at 37°C for 72 hr resulted in an approximate 15% reduction in the biological activity as assessed by [³H]thymidine incorporation. As assessed by bioassay ([³H]thymidine uptake), the cumulative percentage rIL-2 released in vitro at 22°C after 8 hr from rIL-2/poloxamer 407 matrices containing either 30% (w/w) or 35% (w/w) poloxamer 407 was 81.8 ± 1.7 and 82.1 ± 4.7%, respectively. When ELISA was used to determine the amount of rIL-2 released vs time, the corresponding values for the cumulative percentage rIL-2 released were 82.6 ± 10.1 and 40.9 ± 8.8%. Cytotoxicity of rIL-2-stimulated PBLs cultured with poloxamer 407 (0.17%, w/w) toward malignant Daudi cells was significantly (P < 0.05) enhanced compared to controls. Finally, mice injected with the rIL-2/poloxamer 407 formulation (1 × 10⁵ U/inj. q.d. × 3 days) demonstrated a bioequivalent effect of rIL-2-induced natural killer (NK) cell activity in vitro toward malignant murine YAC-1 cells at one-half the standard exogenously administered dose of rIL-2 known to generate enhanced NK lytic activity in mice (1 × 10⁵ U/inj. b.i.d. x 3 days). No untoward systemic side effects were observed for mice injected i.p. with polymer vehicle alone (30%, w/w) (0.15 ml q.d. × 3 days), pH 7 phosphate-buffered saline (PBS) (0.15 ml q.d. × 3 days), rIL-2 formulated with poloxamer 407 (30%, w/w) (1 × 10⁵ U/0.15 ml q.d. × 3 days and 0.5 × 10⁵ U/0.15 ml q.d. × 3 days), or rIL-2 dissolved in PBS (1 × 10⁵ U/0.15 ml b.i.d. × 3 days). Thus, poloxamer 407, N.F., did not denature rIL-2 when the latter was stabilized with human serum albumin (HSA), enhanced the in vitro lytic ability of human rIL-2-stimulated PBLs against malignant Daudi cells, and served as a sustained-release parenteral vehicle for rIL-2 when injected i.p. into mice. Thus, based on these preliminary findings, it appears that poloxamer 407, N.F., may potentially be useful for the formulation and sustained delivery of select protein pharmaceuticals following extravascular administration.     

盐酸布替萘芬阴道用温敏水凝胶的制备及体外释放度的考察

目的:制备盐酸布替萘芬阴道用温敏水凝胶并考察其体外释放度。方法:以泊洛沙姆为基质,筛选最佳处方以达到合适胶凝温度,并利用高效液相色谱法(HPLC)建立含量测定方法考察体外释放度。结果:结果显示以1%盐酸布替萘芬、0.1%山梨酸钾、2%甘油、5%聚山梨酯80、12%泊洛沙姆407及5%泊洛沙姆188为配方制备的温敏水凝胶在35℃时产生胶凝,体外释放度考察结果显示8 h可释放超过90%的药物。结论:本研究制备的盐酸布替萘芬阴道用温敏水凝胶具有很好的温度敏感性及黏附性,具有缓释特性且给药方便,是一种值得开发的药物制剂。     

雌二醇阴道用生物黏附性温敏型凝胶的处方筛选及流变学考察

目的:研制雌二醇阴道用生物黏附性温敏型凝胶(E₂-VTISG),并进行热力学和流变学考察。方法:采用冷法工艺制备E₂-VTISG。采用倒试管法测定胶凝温度(T_gel),以T_gel为考察指标,泊洛沙姆P407,泊洛沙姆P188为主要影响因素,用星点设计-效应面法进行处方筛选。采用黏度计测定表观粘度,采用动态流变学实验测定温敏凝胶在相变过程中的流变参数。结果:雌二醇阴道用生物黏附性温敏型凝胶的最优处方的基质配比为P407:P188:甘油:PCP:尼泊金乙酯=18:2.96:5:0.2:0.2,实测胶凝温度为33.4℃。结论:星点设计-效应面法筛选E₂-VTISG处方预测性良好,流变学结果显示优化后的雌二醇温敏凝胶符合阴道局部用药要求。     

Novel in-situ gel for intravesical administration of ketorolac

The urinary bladder stores urine until the time of urination. Systemic administration of drugs to treat bladder diseases faces several limitations. Therefore, intravesical drug delivery is a promising alternative route of administration. An in-situ gel is used to form a gel inside the bladder cavity and ensure continuous release of the drug even after urination. The objective of the present study was to optimize an in-situ gel formulation of poloxamer and chitosan for intravesical delivery of ketorolac tromethamine. The gelling temperature of the prepared combinations ranged from 20.67 to 25.8?°C. In-vitro release of KT was sustained for up to 7?h using a poloxamer concentration ranging from 17% to 19% and a chitosan concentration ranging from 1% to 2%. Design-Expert® 10 was used to select the optimized formulation (poloxamer/chitosan 17/1.589% w/w) which significantly (p?<?0.05) extended the drug release more than each polymer alone. An ex-vivo study showed the ability of the optimized formulation to sustain drug release after emptying two times to mimic urination. Furthermore, the formed gel adhered to the bladder tissue throughout the time period of the experiment. Intravesical administration of the optimized formulation to rabbits via catheter showed no obstruction of urine flow and continuous release of the drug for 12?h.     

In-situ gel formulations of econazole nitrate: preparation and in-vitro and in-vivo evaluation

Objectives This study describes the in‐situ gelling of econazole nitrate containing thermosensitive polymers composed of poloxamer 407 and 188 as a novel treatment platform for vaginal candidiasis. Methods Aqueous thermosensitive formulations containing 1% of econazole nitrate and poloxamer 407 and/or 188 were prepared and their rheological, mechanical and drug‐release properties determined at 20 ± 0.1°C and/or 37 ± 0.1°C. Based on their biologically suitable thermorheological properties, formulations containing the mixtures of poloxamer 407 and 188 in ratios of 15:15 (F1), 15:20 (F2) and 20:10 (F3) were chosen for comprehensive analysis. Key findings Formulations based on F3 exhibited typical gel‐type mechanical spectra (G′ > G″) at 37°C whereas formulations based on F1 and F2 exhibited properties akin to weakly cross‐linked gels. Texture profile analysis demonstrated that F3 showed the highest cohesiveness, adhesiveness, hardness and compressibility. No statistically significant differences (P > 0.5) were observed in the release of econazole nitrate from the formulations at pH 4.5, which in all cases followed anomalous diffusion kinetics. Formulations based on 20% poloxamer 407:10% poloxamer 188 were chosen for in‐vivo studies and were shown to be effective for the treatment of the vaginal candidiasis. Histopathologic evaluation also supported the effectiveness of the thermosensitive formulation administered intravaginally. Conclusion By careful engineering of the rheological properties, in‐situ thermosensitive gel formulations of econazole nitrate were prepared and were shown to be efficacious in the treatment of vaginal candidiasis.     

In vivo pharmacokinetic and tissue distribution studies in mice of alternative formulations for local and systemic delivery of Paclitaxel: gel, film, prodrug, liposomes and micelles

The aim of this study was to increase the understanding on the pharmacokinetic and tissue distribution of paclitaxel as influenced by formulation approach. For this purpose, various formulations investigated in Swiss mice included liposomes, poloxamer 407 gel and chitosan film for subcutaneous route; and water-soluble methacrylate prodrug, liposomes and poloxamer micelles for systemic administration. During this study, the currently marketed formulation of Cremophor EL of paclitaxel was used as the reference. A highest plasma concentration following intravenous administration of paclitaxel was observed for rigid and 'Stealth((R))' liposomes containing the prodrug while, least was for covalently incorporated paclitaxel micelles. Further, poloxamer micelles demonstrated both the highest mean residence time of 7.34 h and volume of distribution (VSS=4.82 and VZ=5.87 L/kg) for paclitaxel. This was followed by prodrug loaded 'Stealth' liposomes, which showed a mean residence time of 4.96 h but were least distributed into apparent physiological volume (VSS=2.12 and VZ=3.16 L/kg). These results clearly signify the role of formulation/excipient in drug disposition and possible interactions. Importantly, due to decrease in the clearance rate of drug, the area under curve values of paclitaxel increased by 1.64- and 2.5-fold for micellar and prodrug loaded 'Stealth' liposomal formulations, respectively over reference formulation. While thermoreversible gels served to decrease plasma concentration of paclitaxel (8-fold) after subcutaneous administration, systemic levels were totally absent after implantation of films. In tissue distribution studies, maximum percent of paclitaxel was observed in liver for reference formulation, conventional liposomes and micelles whereas highest levels of prodrug and 'Stealth((R))' liposomes were in kidney and spleen, respectively. The novel formulations significantly altered tissue accumulation profiles of paclitaxel relative to the reference formulation, for example, reduction in uptake by heart from liposomes and micelles, as well as the major recognition mechanism for elimination. It is proposed that a combination therapy with liposomes and micelles of paclitaxel for systemic delivery along with implantation of chitosan film for local delivery, may serve not only to improve patient compliance by obliterating the need to administer Cremophor EL, but also increase patient survival.     

Dual controlled release, in situ gelling periodontal sol of metronidazole benzoate and serratiopeptidase: statistical optimization and mechanistic evaluation

In situ gelling syringeable periodontal sol capable of dual controlled delivery of metronidazole benzoate and serratiopeptidase was designed based on 2(3) factorial design with drug, poloxamer 407 and aerosil as independent variables and sol gel transition characteristics, %CDR(48h) and palatability as responses. The sols had agreeable taste, were mucoadhesive, syringeable and inverted into gels at periodontal cavity temperature. F8 with optimal drug release was identified as the best formulation. The dispersion characteristics of poloxamer significantly affected the pharmacotechnical properties of the in situ gelling systems. Extra design checkpoint generated using Design Expert software 8.02 (Stat-Ease, USA) validated the experimental design. Thus a thermoreversible, in situ gelling and syringeable periodontal sol with acceptable taste characteristics that offered controlled release of metronidazole benzoate and serratiopeptidase was developed for application into the periodontal pocket. The developed optimized sol was satisfactory in terms of taste, syringeability, palatability and incorporation of serratiopeptidase as anti-inflammatory agent, has the potential of developing a therapeutically efficacious system for treatment of periodontal inflammatory anaerobic infections.