Current Drug Delivery - Volume 11, Issue 3, 2014

Nanotechnology is being explored in many ways to design a new chemical entity (NCE) to an active pharmaceutical ingredient (API). Of the different nanotechnologies, Nanosuspensions has gained a lot of interest due to its ease of production and applicability to a large number of drugs. This present review article on nanosuspensions is focused on the various principles, production techniques, stability problems, various marketed formulations and current trends associated with the nanosuspensions.

Since the discovery of Helicobacter pylori (H. pylori) in the early 1980s, its eradication has been one of the most important global challenges in gastroenterology. Various circumstances make the treatment with antimicrobials particularly difficult. One problem has been that antibiotics commonly used were designed for the treatment of infections throughout the body rather than for delivering high concentrations locally within the stomach. Many gastroretentive dosage forms were developed in order to eradicate the infection, yet additional advancements are still needed to eliminate the infection completely and decrease its prevalence worldwide. An overview on different antimicrobials and a literature survey about different drug delivery systems used in eradication of H. pylori infection are presented in this review.

The work investigates the formulation and evaluation of microemulsions containing olive oil, Tween 80 and isopropyl alcohol for transdermal candesartan cilexetil delivery. The pseudoternary phase diagram was constructed to determine composition of microemulsions. These formulated microemulsions were evaluated for in vitro skin permeation and stability. The microemulsion containing 72 % olive oil, 8 % water, 15 % Tween 80, and 5 % isopropylalcohol showed maximum viscosity of 29.54±0.32 mPas, average small droplet size of 180.90 nm, smaller polydispersity index of 0.37, zeta potential of –12.20 and maximum candesartan cilexetil permeation flux of 0.49±0.05 μg/cm2/h through excised porcine skin. The degradation of candesartan cilexetil microemulsions after 3 months storage was found low and its shelf-life was calculated as 3.92 years at room temperature.

The spherical microspheres consisting of Furosemide loaded sodium alginate and along with HPMC E50 or sodium CMC as mucoadhesive polymers in different ratios were prepared using ionic gelation technique. Calcium chloride was used as crosslinking, to retard the drug release from the mucoadhesive microspheres. The prepared mucoadhesive microspheres were subjected for evaluation of various parameters like production yield, particle size, encapsulation efficiency, mucoadhesion test and in vitro dissolution profile studies. Formulations were subjected to DSC study and SEM analysis. The in vitro release data were well fit into Higuchi and Korsmeyer-Peppas model and followed non-Fickian diffusion mechanism.

In the present study, ethosomal and liposomal formulations containing tamoxifen citrate were prepared and evaluated for their penetration properties in human cadaver skin using Franz diffusion cell and confocal laser scanning microscope (CLSM). The results clearly revealed that ethosomal vesicles showed a better drug permeation profile than that of liposomal vesicles. In addition, low fluorescence intensity in CLSM was recorded with liposomes as compared to ethosomes, indicating lower cumulative amount of drug permeation from liposomal vesicles. Furthermore, CLSM showed uniform fluorescence intensity across the entire depth of skin in ethosomal treatment, indicating high penetrability of ethosomal vesicles through human cadaver skin. In contrast, low penetrability of conventional liposomal vesicles was recorded as penetration was limited to the 7th section (i.e. upper epidermis layer) of skin as evident from visualization of intact liposomal vesicles in CLSM.

An oral pharmaceutical suspension has been one of the most favorable dosage forms for pediatric and geriatric patients or patients unable to tolerate solid dosage forms. The liquid form is preferred because of the ease of swallowing and flexibility in the administration of doses. This emerging area of suspensions as applied to the pharmaceutical field are discussed in the current article enlightening the vision of the readers towards pharmaceutical formulations including nanosuspensions, non-aqueous suspensions and modified release suspensions. The emphasis in the article focuses on the essential principles involved in the process of formation of different types of suspensions and their applications, since novel oral suspensions have potential to provide various strategy systems.

The aim of the present study was to develop and characterize rivastigmine loaded Human Serum Albumin (HSA) nanoparticles (NPs) for sustained release. Rivastigmine tartrate (RT) is a short acting cholinesterase inhibitor (ChEI) used for Alzheimer’s disease (AD). In the present study sustained release nanoparticulate formulation of RT was prepared, optimized (using 32 factorial design) and characterized (using biodegradable polymer HSA as a carrier). HSA NPs were prepared by desolvation-crosslinking technique using ethanol with variable drug/polymer ratios (1:1, 1:2, 1:3, and 1:5) and using glutaraldehyde as a crosslinking agent. All prepared nanoparticles were coated with polysorbate-80 to facilitate brain targeting via endocytosis. Effect of key formulation variables on particle size (PS) and percentage drug entrapment (PDE) of NPs was studied by using 32 factorial design. Among different ratios studied, 1:2 showed minimum PS of 83.71 ± 4.2 nm with highest PDE of 81.46 ± 0.76 %. FTIR interpretation showed that there is no interaction between the drug and excipients used, DSC thermograms indicated that RT was dispersed as an amorphous state in HSA NPs. SEM studies indicated that the drug was completely entrapped in HSA NPs. In vitro studies showed 55.59 ± 3.80% release of drug from HSA NPs in 12 h. The experimental results showed the suitability of HSA nanoparticles as a potential carrier for providing sustained delivery of RT.

The gastroretentive drug delivery system is site-specific and allows the drug to remain in the stomach for a prolonged period of time so that it can be released in a controlled manner in gastrointestinal tract. The present study was carried out to develop a gastroretentive drug delivery system using isabgol as an excipient to prolong the residence time of the model drug lisinopril in the stomach. The gastroretentive ability of isabgol was increased by addition of NaHCO3 as a gas-generating agent while its mucoadhesive property was enhanced by incorporation of HPMC-K4M. The drug, NaHCO3 and HPMC-K3M were imbibed on isabgol-husk as per entrapment efficiency of the isabgol-husk. After drying, the product was filled in a hard gelatin capsule and evaluated for its buoyancy, mucoadhesive properties, swelling index and in vitro drug release. The lisinopril released through isabgol was delayed by 12 hours when compared to a preparation available on the market which released the complete drug in 0.5 hours. The drug release study of lisinopril from the formulation follows first order kinetics using a diffusion controlled mechanism. The results from the present study revealed that isabgol can be used as a potential excipient for the formulation of gastroretentive drug delivery systems in the near future.

The study investigates the combined influence of three independent variables in preparation of aceclofenac ternary solid dispersion (SD) by kneading method. A 3-factor, 3-level Box-Behnken design was used. Independent variables selected were microcrystalline cellulose (Avicel 200 = X1), hydroxypropyl methylcellulose-5 cps (HPMC E-5 = X2), and ratio of drug to polymer mixture (X3). Fifteen batches were prepared and evaluated for angle of repose and percentage drug release at 5 minutes (Q5). The transformed values of variables were subjected to multiple regression analysis to establish a second-order polynomial equation. Contour plots were constructed to evaluate the effects of X1, X2 and X3 on Q5 and angle of repose. Model was validated for accurate prediction of Q5 and angle of repose (AR) by performing checkpoint analysis. The computer optimization process and contour plots predict the levels of independent variables as X1= +0.5, X2 = -1 and X3 = +0.35 for maximized response of Q5 with better flow property. The stability study during 6 months confirms that aceclofenac exhibits high stability in solid dispersion. In vivo studies indicate that optimized ternary solid dispersion provides rapid pharmacological responses in mice and rats compared to marketed formulation.

Floating pulsatile is combined approach designed according to circadian rhythm to deliver the drug at right time, in right quantity and at right site as per pathophysiological need of disease with prolong gastric residence and lag phase followed by burst release. As the migraine follows circadian rhythm in which headache is more painful at the awakening time, the dosage form should be given during night time to release drug when pain get worsen. Present work deals with formulation and optimization of floating pulsatile tablet of sumatriptan succinate. Core tablet containing crospovidone as superdisintegrant (10%) showed burst release. Lag time was maintained using swellable polymer as polyoxN12K and xanthum gum. 32 experimental design was carried out. Developed formulations were evaluated for physical characteristics, in vitro and in vivo study. Optimized batch F2 with concentration of polyox N12K (73.43%) and xanthum gum (26.56%) of total polymer weight showed floating lag time 15±2 sec, drug content 99.58±0.2 %, hardness 6±0.2 Kg/cm2 and drug release 99.54±2% with pulsatile manner followed lag period of 7±0.1h. In vivo x-ray study confirms prolong gastric residence of system. Programmable pulsatile release has been achieved by formulation F2 which meet demand of chronotherapeutic objective of migraine.

5-Fluorouracil (5-FU) is one of the most effective antineoplastic agents used for the treatment of skin cancers and actinic keratosis (AK). Currently commercial formulation for topical 5-FU administration is available in the form of solution or cream. Commercial topical formulations are associated with the limitation of very short retention time at the administration site resulting in very poor skin permeation and deposition of drug. In the present study attempt was made for the preparation, optimization and characterization of bioadhesive gel formulations for localized delivery of 5-FU. Four bioadhesive gel formers, Carbopol 934, Carbopol 980, Methylcellulose (MC) and Poloxamer 188 were selected for the preparation of 5-FU bioadhesive gel formulations. The formulations were characterized for characteristic parameters including bioadhesive strength, skin deposition and interaction study. Carbopol 934 based bioadhesive gel formulation at the concentration of 1.5% w/w showed the best physicochemical properties such as viscosity (2670±12.2 cP), which was similar to the value obtained with the marketed cream (2870±14.4 cP), highest skin deposition (1290±56.4μg) and bioadhesive strength (18.62 gf). Cutaneous irritation of optimized bioadhesive gel formulations was also tested using the Draize test and only very slight erythema and no oedema was observed. In comparison, marketed formulation showed well defined erythema along with oedema formation. The result of the present study demonstrated that formulation of Carbopol 934 based 5-FU bioadhesive gel is a better alternative to the traditional cream base for enhanced topical delivery of 5-FU. The developed formulation will have the ease of application, better skin deposition and sustained release characteristic with reduced skin toxicity.

Oral mucositis is one of the major side effects of cancer chemotherapy (30-76%) and radiotherapy (over 50%). Current palliative treatments of oral mucositis include specialized agents like pelifermin, platelet derived factors etc. or oral hygienic agents which suffered from various drawbacks like systemic side effect, least effect owing to fast wash out of buccal mucosa, patient unfriendly delivery systems, and mere symptomatic relief. In this research work, N-succinyl chitosan gel delivery system of microemulsified eugenol, honey and sodium hyaluronate was prepared to explore their multiple and synergistic effects on various pathological factors of oral mucositis. N-succinyl chitosan was synthesized in our laboratory and loaded with microemulsified eugenol (10% v/v), honey (10% v/v) and sodium hyaluronate (0.2% w/v) to prepare orogel with optimum pH, spreadability, mucoadhesion strength, and viscosity. In vitro eugenol release from N-succinyl chitosan gel after 8 hours in PBS (pH-6.4) was found to be 87.45±0.14%, which was better in comparison to that released from chitosan gel. Ex vivo penetration studies using rat buccal mucosal tissue also suggested better J-efflux of eugenol through N-succinyl chitosan in comparison to chitosan gel with enhancement ratio (ER) of 1.71. The antimicrobial effect of N-succinyl chitosan based orogel against S. aureus and C. albicans efficacy was found to be statistically high in comparison to chitosan based orogel as well as marketed formulation of chlorhexidine (p<0.05). The N-succinyl chitosan orogel in 5-fluoro uracil induced oral mucositis animal (Wistar rats) model showed enhanced survival ratio, weight gain and high tissue regeneration activity than chitosan gel formulation within 15 days. The formulation was successful in elevating the survival and reducing the inflammation in the oral mucosa of animals compared to disease control (p<0.05) and hence suggesting the potential of N-succinyl chitosan orogel in the treatment of oral mucositis.