Anticancer drug delivery: Investigating the impacts of viscosity on lipid-based formulations for pulmonary targeting.

Pulmonary drug delivery via aerosolization is a non-intrusive method for achieving localized and systemic effects. The aim of this study was to establish the impact of viscosity as a novel aspect (i.e., low, medium and high) using various lipid-based formulations (including liposomes (F1-F3), transfersomes (F4-F6), micelles (F7-F9) and nanostructured lipid carriers (NLCs; F10-F12)) as well as to investigate their impact on in-vitro nebulization performance using Trans-resveratrol (TRES) as a model anticancer drug. Based on the physicochemical properties, micelles (F7-F9) elicited the smallest particle size (12-174 nm); additionally, all formulations tested exhibited high entrapment efficiency (>89 %). Through measurement using capillary viscometers, NLC formulations exhibited the highest viscosity (3.35-10.04 m2/sec). Upon using a rotational rheometer, formulations exhibited shear-thinning (non-Newtonian) behaviour. Air jet and vibrating mesh nebulizers were subsequently employed to assess nebulization performance using an in-vitro model. Higher viscosity formulations elicited a prolonged nebulization time. The vibrating mesh nebulizer exhibited significantly higher emitted dose (ED), fine particle fraction (FPF) and fine particle dose (FPD) (up to 97 %, 90 % and 64 µg). Moreover, the in-vitro release of TRES was higher at pH 5, demonstrating an alignment of the release profile with the Korsmeyer-Peppas model. Thus, formulations with higher viscosity paired with a vibrating mesh nebulizer were an ideal combination for delivering and targeting peripheral lungs.

Fabrication, characterization and optimization of nanostructured lipid carrier formulations using Beclomethasone dipropionate for pulmonary drug delivery via medical nebulizers.

Aerosolization is a non-invasive approach in drug delivery for localized and systemic effect. Nanostructured lipid carriers (NLCs) are new generation versatile carriers, which offer protection from degradation and enhance bioavailability of poorly water soluble drugs. The aim of this study was to develop and optimize NLC formulations in combination with optimized airflow rates (i.e. 60 and 15 L/min) and choice of medical nebulizers including Air jet, Vibrating mesh and Ultrasonic nebulizer for superior aerosolization performance, assessed via a next generation impactor (NGI). Novel composition and combination of NLC formulations (F1 - F15) were prepared via ultrasonication method, employing five solid lipids (glycerol trimyristate (GTM), glycerol trilaurate (GTL), cetyl palmitate (CP), glycerol monostearate (GMS) and stearic acid (SA)); and three liquid lipids (glyceryl tributyrate (GTB), propylene glycol dicaprylate/dicaprate (PGD) and isopropyl palmitate (IPP)) in 1:3 w/w ratios (i.e. combination of one solid and one liquid lipid), with Beclomethasone dipropionate (BDP) incorporated as the model drug. Out of fifteen BDP-NLC formulations, the physicochemical properties of formulations F7, F8 and F10 exhibited desirable stability (one week at 25 °C), with associated particle size of ~241 nm, and >91% of drug entrapment. Post aerosolization, F10 was observed to deposit notably smaller sized particles (from 198 to 136 nm, 283 to 135 nm and 239 to 157 nm for Air jet, Vibrating mesh and Ultrasonic nebulizers, respectively) in all stages (i.e. from stage 1 to 8) of the NGI, when compared to F7 and F8 formulations. Six week stability studies conducted at 4, 25 and 45 °C, demonstrated F10 formulation stability in terms of particle size, irrespective of temperature conditions. Nebulizer performance study using the NGI for F10 identified the Air jet to be the most efficient nebulizer, depositing lower concentrations of BDP in the earlier stages (1-3) and higher (circa 82 and 85%) in the lateral stages (4-8) using 60 and 15 L/min airflow rates, when compared to the Vibrating mesh and Ultrasonic nebulizers. Moreover, at both airflow rates, the Air jet nebulizer elicited a longer nebulization time of ~42 min, facilitating aerosol inhalation for prophylaxis of asthma with normal tidal breathing. Based on characterization and nebulizer performance employing both 60 and 15 L/min airflow rates, the Air jet nebulizer offered enhanced performance, exhibiting a higher fine particle dose (FPD) (90 and 69 µg), fine particle fraction (FPF) (70 and 54%), respirable fraction (RF) (92 and 69%), and lower mass median aerodynamic diameter (MMAD) (1.15 and 1.62 µm); in addition to demonstrating higher drug deposition in the lateral parts of the NGI, when compared to its counterpart nebulizers. The F10 formulation used with the Air jet nebulizer was identified as being the most suitable combination for delivery of BDP-NLC formulations.

A Facile and Novel Approach to Manufacture Paclitaxel-Loaded Proliposome Tablet Formulations of Micro or Nano Vesicles for Nebulization.

PURPOSE: The aim of this study was to develop novel paclitaxel-loaded proliposome tablet formulations for pulmonary drug delivery. METHOD: Proliposome powder formulations (i.e. F1 - F27) were prepared employing Lactose monohydrate (LMH), Microcrystalline cellulose (MCC) or Starch as a carbohydrate carriers and Soya phosphatidylcholine (SPC), Hydrogenated soya phosphatidylcholine (HSPC) or Dimyristoly phosphatidylcholine (DMPC) as a phospholipid. Proliposome powder formulations were prepared in 1:5, 1:15 or 1:25 w/w lipid phase to carrier ratio (lipid phase; comprising of phospholipid and cholesterol in 1:1 M ratio) and Paclitaxel (PTX) was used as model anticancer drug. RESULTS: Based on flowability studies, out of 27 formulations; F3, F6, and F9 formulations were selected as they exhibited an excellent angle of repose (AOR) (17.24 ± 0.43, 16.41 ± 0.52 and 15.16 ± 0.72°), comparatively lower size of vesicles (i.e. 5.35 ± 0.76, 6.27 ± 0.59 and 5.43 ± 0.68 µm) and good compressibility index (14.81 ± 0.36, 15.01 ± 0.35 and 14.56 ± 0.14) via Carr's index. The selected formulations were reduced into Nano (N) vesicles via probe sonication, followed by spray drying (SD) to get a dry powder of these formulations as F3SDN, F6SDN and F9SDN, and gave high yield (>53%) and exhibited poor to very poor compressibility index values via Carr's Index. Post tablet manufacturing, F3 tablets formulation showed uniform weight uniformity (129.40 ± 3.85 mg), good crushing strength (14.08 ± 1.95 N), precise tablet thickness (2.33 ± 0.51 mm) and a short disintegration time of 14.35 ± 0.56 min, passing all quality control tests in accordance with British Pharmacopeia (BP). Upon nebulization of F3 tablets formulation, Ultrasonic nebulizer showed better nebulization time (8.75 ± 0.86 min) and high output rate (421.06 ± 7.19 mg/min) when compared to Vibrating mesh nebulizer. PTX-loaded F3 tablet formulations were identified as toxic (60% cell viability) to cancer MRC-5 SV2 cell lines while safe to normal MRC-5 cell lines. CONCLUSION: Overall, in this study LMH was identified as a superior carbohydrate carrier for proliposome tablet manufacturing in a 1:25 w/w lipid to carrier ratio for in-vitro nebulization via Ultrasonic nebulizer.

The effect of ethanol evaporation on the properties of inkjet produced liposomes.

BACKGROUND: Inkjet method has been used to produce nano-sized liposomes with a uniform size distribution. However, following the production of liposomes by inkjet method, the solvent residue in the product could have a significant effect on the properties of the final liposomes. OBJECTIVE: This research paper aimed to find a suitable method to remove ethanol content and to study its effect on the properties of the final liposomal suspension. METHOD: Egg phosphatidylcholine and lidocaine were dissolved in ethanol; and inkjet method at 80 kHz was applied to produce uniform droplets, which were deposited in an aqueous solution to form liposomes. Dry nitrogen gas flow, air-drying, and rotary evaporator were tested to remove the ethanol content. Liposome properties such as size, polydispersity index (PDI), and charge were screened before and after ethanol evaporation. RESULTS: Only rotary evaporator (at constant speed and room temperature for 2 h) removed all of the ethanol content, with a final drug entrapment efficiency (EE) of 29.44 ± 6.77%. This was higher than a conventional method. Furthermore, removing ethanol led to liposome size reduction from approximately 200 nm to less than 100 nm in most samples. Additionally, this increased the liposomal net charge, which contributed to maintain the uniform and narrow size distribution of liposomes. CONCLUSION: Nano-sized liposomes were produced with a narrow PDI and higher EE compared to a conventional method by using an inkjet method. Moreover, rotary evaporator for 2 h reduced effectively the ethanol content, while maintaining the narrow size distribution. Graphical abstract.

Paclitaxel-loaded micro or nano transfersome formulation into novel tablets for pulmonary drug delivery via nebulization.

A simplistic approach was adopted to manufacture novel paclitaxel (PTX) loaded protransfersome tablet formulations for pulmonary drug delivery. The large surface area offered by the pulmonary system acts as a desirable site for anti-cancer drug deposition; offering localized effect within the lungs. Protransfersomes are dry powder formulations, whereas transfersomes are liquid dispersions containing vesicles generated from protransfersomes upon hydration. Protransfersome powder formulations (F1-F27) (referred as Micro formulations based on transfersomes vesicles size post hydration) were prepared by employing a phospholipid (Soya phosphatidylcholine (SPC)), three different carbohydrate carriers (Lactose monohydrate, LMH; Microcrystalline cellulose, MCC; and Starch), three surfactants (i.e. Span 80, Span 20 and Tween 80) in three different lipid phase to carrier ratios (i.e. 1:05, 1:15 and 1:25 w/w), with the incorporation of PTX as a model drug. Hydrophobic chain of SPC may enhance PTX solubility, entrapment and targetted delivery via transfersome vesicles. Out of the 27 Micro protransfersome formulations, PTX-loaded LMH powder formulations F3, F6 and F9 (i.e. 1:25 w/w lipid phase to carrier ratio) exhibited excellent powder flowability via angle of repose (AOR) and good compressibility index due to associated smaller and uniform particle size and shape of LMH. Following hydration, these formulations also showed smaller volume median diameters (VMD) in micrometres (5.65 ± 0.85-6.76 ± 0.61 µm) and PTX entrapment of 93-96%. Hydrated transfersome formulations (F3, F6 and F9) were converted into Nano size via probe sonication and referred to as Nano formulations. These Nano formulations were converted into dry powder via spray drying (SD) (F3NSD, F6NSD and F9NSD) or freeze drying (FD) (F3NFD, F6NFD and F9NFD). Post manufacture of protransfersome tablets (i.e. 9 formulations), quality control tests were conducted in accordance to British Pharmacopeia (BP). Only the Micro formulations protransfersome tablets (i.e. F3, F6 and F9) passed the uniformity of weight test, exhibited high crushing strength and tablet thickness when compared to SD or FD protransfersome tablets. Micro protransfersome formulations (i.e. F3, F6 and F9) into tablets demonstrated a shorter nebulization time and high output rate when using Ultrasonic nebulizer compared to Vibrating mesh nebulizer (i.e. Omron NE U22). Based on formulations, characterizations and nebulizer performance; Micro protransfersome tablet formulations F3, F6 and F9 (i.e. 1:25 w/w) and Ultrasonic nebulizer were found to be a superior combination, eliciting enhanced output efficiency. Moreover, PTX-loaded F3, F6 and F9 tablet formulations (10%) exhibited toxicity (60, 68 and 67% cell viability) to cancer MRC-5 SV2 (i.e. immortalized human lung cells) while safe to MRC-5 (normal lung fibroblast cells) cell lines.

Formulation and optimisation of novel transfersomes for sustained release of local anaesthetic.

OBJECTIVE: To investigate the effect of formulation parameters on the preparation of transfersomes as sustained-release delivery systems for lidocaine and to develop and validate a new high-performance liquid chromatography (HPLC) method for analysis. METHOD: Taguchi design of experiment (DOE) was used to optimise lidocaine-loaded transfersomes in terms of phospholipid, edge activator (EA) and phospholipid : EA ratio. Transfersomes were characterised for size, polydispersity index (PDI), charge and entrapment efficiency (%EE). A HPLC method for lidocaine quantification was optimised and validated using a mobile phase of 30%v/v PBS (0.01 m) : 70%v/v Acetonitrile at a flow rate of 1 ml/min, detected at 255 nm with retention time of 2.84 min. The release of lidocaine from selected samples was assessed in vitro. KEY FINDINGS: Transfersomes were 200 nm in size, with PDI ~ 0.3. HPLC method was valid for linearity (0.1-2 mg/ml, R2 0.9999), accuracy, intermediate precision and repeatability according to ICH guidelines. The %EE was between 44% and 56% and dependent on the formulation parameters. Taguchi DOE showed the effect of factors was in the rank order : lipid : EA ratio Ëƒ EA type Ëƒ lipid type. Optimised transfersomes sustained the release of lidocaine over 24 h. CONCLUSION: Sustained-release, lidocaine-loaded transfersomes were successfully formulated and optimised using a DOE approach, and a new HPLC method for lidocaine analysis was developed and validated.

Surfactant Effects on Lipid-Based Vesicles Properties.

Understanding the effect of surfactant properties is critical when designing vesicular delivery systems. This review evaluates previous studies to explain the influence of surfactant properties on the behavior of lipid vesicular systems, specifically their size, charge, stability, entrapment efficiency, pharmacokinetics, and pharmacodynamics. Generally, the size of vesicles decreases by increasing the surfactant concentration, carbon chain length, the hydrophilicity of the surfactant head group, and the hydrophilic-lipophilic balance. Increasing surfactant concentration can also lead to an increase in charge, which in turn reduces vesicle aggregation and enhances the stability of the system. The vesicles' entrapment efficiency not only depends on the surfactant properties but also on the encapsulated drug. For example, the encapsulation of a lipophilic drug could be enhanced by using a surfactant with a low hydrophilic-lipophilic balance value. Moreover, the membrane permeability of vesicles depends on the surfactant's carbon chain length and transition temperature. In addition, surfactants have a clear influence on pharmacokinetics and pharmacodynamics such as sustaining drug release, enhancing the circulation time of vesicles, improving targeting and cellular uptake.