Chitosan is natural biodegradable polymer and highly mucoadhesion properties which are used to enhance the residence time of drug particles in the nasal cavity, until now the detail of degradation of chitosan microspheres have not been studied in detail. For this purpose four formulation of ropinirole loaded chitosan microspheres were prepared using Mini B-290 Buchi spray dryer in various drug to polymer ratio.

Summary by Sneha Subramanian – 22/06/2012

Current Drug Delivery, 2008, 5, 207-214 207

1567-2018/08 $55.00+.00 © 2008 Bentham Science Publishers Ltd.

Sanjay K. Jain*, Yashwant Gupta, Anekant Jain and Sadia Amin

In this experiment, elastic liposomes are used for the delivery of Meloxicam-β-Cyclodextrin vie skin.

Meloxicam has anti-inflammatory activity which is used for the treatment of ostereostasis and rheumatoid arthritis. This drug is poorly soluble in water; hence, its absorption from GI track is prolonged. This leads to many side effects like ulceration and bleeding. Cyclodextrin has hydrophobic central cavity and hydrophilic outer surface. They form inclusion complex with the drug and improves stability, solubility and dissolution rate of the drug. Recently various vesicles are used for the effective delivery of drug via Transdermal route, they include liposomes and niosomeswhich have their own mechanism to deliver drug. These vesicles are obstructed by the layer of the skin called stratum corneum which is very thick. Hence, a specialised vesicle which is elastic is developed to overcome this problem. They vary from liposomes and niosomes by their characterisctic fluid membrane and can easily pass through the tough stratum corneum. They have the ability to sqeeze and bend, hence, can pass though small intracellular space.  Transdermal water gradient aids it in this movement of elastic liposomes. This work aims at he delivery of Meloxicam-β-Cyclodextrin complex along with the elastic vesicle to exploit the characteristics of both the carriers.

Meloxicam-β-Cyclodextrin complex was taken in the molar ratio 1:2. This complex was watted in water and was kneaded to paste. This method is called kneading method. This paste was stirred continuously till it peeled off the walls of the mortar. This preparation was then dried in rotary evaporator at 45° which was then sieved. The particles below 50-100µm was used for this experiment.

Solubility studies – This was carried out according to the method given by Higuchi and Connors. In this method excess amount of Meloxicam was transferred into 25ml of aqueous solution containing β –Cyclodextrin from 0-10M/L concentration. It is also shaken for 48hours at room temperature. After filtration, their spectrophotometric studies were carried out at 361nm to estimate the quantity of Meloxicam. Their mixtures were shaken till three consecutive samples estimated same amount of drug.

Differential scanning calorimetry – All samples were taken in 0.5-1mg size range and scanned in temperature 100-270°C/10°/min under nitrogen atmosphere.

X- ray powder Diffractometry (XRD) – was used for the interval of 10-60°/20. The conditions were taken as follows: voltage, 50 kV; current , 200mA; angular speed, 3°/min and angular step of 0.02°

FTIR studies – In this technique, the samples are vacuum drived for 12 hours before studies. The samples- Meloxicam, β-Cyclodextrin and Meloxicam-β-Cyclodextrin mixed with potassium bromine (100mg) and compressed with palate.

Elastic liposomes are prepared by conventional rotary evaporation sonication method. Here HSPC and span80 (85:15w/w) was taken in a clean dry round bottom flask. To this organic solvent- chloroform:methanol  (2:1 v/v) was used to dissolve the lipid phase. This organic solvent was removed rotary evaporation above phase transition temperature. This thin film was hydrated with PBS (pH 6.5) containing Meloxicam/ Meloxicam-β-Cyclodextrin complex by rotation at 60rpm for 1hour at 55°C. This was kept for annealing for 2 hours to form multilamellar vesicles (MLVs) and was then was sonicated using probe sonicator for 20mins at 40W. This sonicated vesicles were extruded between 100-200nm polycarbonate membranes. The final lipid drug concentration was 5% wv and 1%wv and similarly Rhodaminered loaded elastic liposomes were prepared.

Morphology was visualised using TEM at voltage of 100KV. For this a drop of sample was kept of the carbon-coated copper and to leave a thin film and before drying was negatively stained with 1% PTA. After the sample was stained and dried and was viewed under TEM. The size and size distribution was determined using DLS method-dynamic light scattering . All measures were conducted in triplicates

Unentrapped drugs were separated using minicolumn centrifuge method. The separated liposomes were separated using 0.1% triton X-100 and was analysed for drug content at 361nm.

These elastic vesicles were extruded through the polycarbonate filter of 50nm diameter with 200ml capacity barrel at 2.5 bar pressure for 10mins. Vesicular sizes were compared before and after extrusion and were repeated.

The in-vitro studies were carried out using dialysis membrane and Franz diffusion cell.

The maximum drug solubility was at 4mM/L concentration of Meloxicam-β-Cyclodextrin. The stability constant (Kc) of Meloxicam and Meloxicam-β-Cyclodextrin complex was calculated

The thermal behaviour of Meloxicam and Meloxicam-β-Cyclodextrin was studies using DSC to confirm the formation of solid complex. The thermogram of Meloxicam-β-Cyclodextrin shows an endothermic peak at 173.8°C while the DSC pattern showed a very diminished melting endotherm of Meloxicam which was shifted to 249°C suggesting a complex formation in 1:2 molar ratio and indicating that the drug has been engulfed in the Cyclodextrin cavity.

The X-ray pattern of Meloxicam and β-Cyclodextrin are shown in the above figure.The XRD of pure of Meloxicam and β-Cyclodextrin are intense and sharp. Thus, inclusion complex indicates their crystalline nature. The inclusion complex shows a completly different pattern which cannot be distinguished from the peak of of Meloxicam. This confirms the existence of new compound at 1:2 molar ratio.

TEM revealed that they are unilamellar and spherical in shape. Precipitation of dry crystals was observed in drug loaded liposomes. This was due to the lower stability of the complex of Meloxicam with native cyclodextrin, part of the drug, less strongly complexed with Cyclodextrin was recrystalized in the aqueous solution during the elastic liposome preparation.

It is observed that the size of drug loaded liposome and empty liposome are almost similar. Larger vesicles are obtained in the presence of Meloxicam-β-Cyclodextrin complex. Polydispersion index is less than 1 indicating narrow size distribution of both formulations. After the entrapment studies , high entrapment of Meloxicam was observed due to its small size as compared to Meloxicam-β-Cyclodextrin complex. This may be due to the lower stability of the complex of Meloxicam with mature cyclodextrin.

The combined effect of using both elastic liposomes and cyclodextrin for Transdermal delivery was studies in this experiment Anti-inflamatory drug Meloxicam was used as a sample drug. Use of cyclodextrin increased the drug’s dissolution property. This increase in water solubility increased its entrapment in the internal aqueous phase of elastic vesicle. This in turn improved the permeability of drug through the skin.

This post by Iftikhar Khan

Corticosteroid drugs are oftenly used as a prophylaxis for asthmatic patients and the method of administration is m ore important for its proper activity. Beclomethasone dipropionate (BDP) produce s some systemic side effects like skin changes, adrenocortical suppression and cataract formation by using dry formulation. In addition, pulmonary delivery of BDP causes Candida infection. For minimising the side effect the drug formulation should be applied to the specific side of action. However, it was noticed that only 10% of the dry powder formulation reaches to the deep lung using Rotahaler, Spinhaler and Diskhaler because most of the drug deposit to the upper respiratory tract from where they swallowed  and absorbed systemically through gastrointestinal tract (GIT). So, by preparing the better formulation and drug delivery method reduces most of the side effects. And in this experiment a drug Beclomethasone dipropionate (BDP) was mixed with carrier lactose in two different forms i.e. coarse and fine lactose. The formulation of all three content as a ternary mixture was checked for their homogeneity and with the delivery of BDP. And it was found that the combination of coarse lactose with fine lactose and BDP minimise the aggregation and maximise the dispersion. However, the controlled amounts of both lactose (CL and FL) play a key role in the flowability of powder, dispersion and stability of the powder formulation.

Coarse lactose (CL) was prepared using air jet sieve and the lactose particles were collected from 63- 90 um in size after 15 minutes of shaking. Air-jet mill was used for the micronisation of fine lactose (FL) and particle less than 63 um was passed once through the jet mill. Both the sample were collected and stored at 50 C for 24 hours and then placed in dedicator over silica gel to protect it from moisture and to use for further investigation. Particle size characterization was done by using Scanning electron microscopy (SEM), where sample was placed on the stub and then coated with gold. Six formulation were prepared using CL, FL and BDP altogether with different mixing sequence and using two different ratios i.e. 64.1 : 3.4 : 1 and 65.8 : 1.7 : 1 w/w. A Turbula mixer was used for powder mixing at 90-95 rpm. In each formulation the first two components were mixed for a predetermined time (15 or 60 minutes) and than a third ingredient was added and mixed for the same time (15 or 60 minutes) for both ratios. BDP and CL in an only ratio of 67.1 : 1 was used as control.

High performance liquid chromatography (HPLC) was used for the analysis of BDP. Methanol and water (7:3) ratio was used as a mobile phase with 0.8 ml/min of flow rate and UV detector was set at 239nm. A calibration curve was prepared from standard solution between 0.1-20.0 ug/ml in range. Each formulation containing a sample of 33 + mg was taken and assayed for by HPLC for the content of BDP.

Particle size of aerosolised BDP was measured using twin stage impinger (TI), a Rotahaler was used containing 33 + mg of powder as a delivery device. A mobile phase (7 ml) was placed in each of the upper and lower parts of the twin impinger. Capsule was placed in the Rotahaler and a rubber moulded mouthpiece was used to attach Rotahaler with throat piece of the impinger. A vacuum pump was set at 60 l/min of flow rate and the dose was released for 5 seconds under these conditions and re-run for the further 7 seconds. The same procedure was repeated for 5 capsules in total for each formulation. The capsule shells, mouth piece and the Rotahaler were washed with the mobile phase to analyse it for the retained amount of drug. The samples from both upper and lower parts of TI were collected and analysed using HPLC method.

In conclusion the addition of fine lactose to the mixture of BDP with coarse lactose as a binary mixture did not affect the mixing uniformity.  The addition of BDP into the binary mixture of CL and FL (became ternary mixture) however showed a reduced in the homogeneity. And the presence of 2.5 % w/w fine lactose in the formulation exhibited an increase dispersion and deaggregation of BDP during aerosolization with an improved fine particle fraction (FPF) and fine particle dispersion (FPD). In addition, it was observed that 60 minutes mixing is better regardless of the mixing pattern of the ingredients than 15 minutes mixing.

Summary by Sneha Subramanian on the paper

Proniosomes used as a drug delivery

Proniosome is basically a dry formulation in which a carrier is coated with a suitable non-ionic surfactant (2000. Hu and Rhodes) and cholesterol (increase the rigidity of niosomal membrane) by dissolving them into an organic solvent. They can be prepared by slurry method using rotary evaporator. In this method a carrier (sucrose, lactose, trehalose and mannitol) is taken in a round bottom flask and a non-ionic surfactant (span 20, 60, 80) with cholesterol and drug (hydrophobic) is dissolved in organic solvent (ethanol or chloroform). Then this solvent is poured into the round bottom flask to make slurry, if the solvent is not enough to make slurry then extra organic solvent can be used to get the desire material. A vacuum and water bath is used in the rotary evaporator to evaporate the organic solvent and allow the solvent phase to make a layer of lipid phase over the carrier. The proniosome can be flushed with nitrogen to remove all the organic solvent. This method can be used to increase the stability of the formulation. Non-ionic surfactant are used instead of phospholipids to get the higher physical and chemical stability (2000. Hu and Rhodes). These substances are biodegradable, biocompatible and have low toxicity (2003. Youan) (2008. Abdelbary) for example sucrose stearate consists of both polar and non-polar group and the combination is due to the ester formation between these two molecules. Sucrose belongs to carbohydrates class and Stearate from fatty acid (palmitic, lauric, stearic acid). So, it acts the same as phospholipid and can entrapped both hydrophilic and lipophilic drugs (2008.Abdelbary).

It is converted into niosomal dispersion by hydration with aqueous solution before administration (2010. Sankar et al), (1998. Vora et al). Niosomes derived from Proniosomes are better (size distribution) than the niosomes prepared from conventional method (2010.Sudhamani.) (2010. Sankar et al). The Proniosomes-based niosomes are more stable both during storage and sterilization. Proniosomes decreases the problems associated with niosomes like fusion, aggregation and leakage of drug (2008.Abdelbary) (2000.Hu and Rhodes). Proniosomes (dry formulation) enhance the transportation, measurement, distribution and storage (2007. Solanki et al) (2010. Sudhamani), (2008. Abdelbary). And this is the property which makes it potentially more suitable for active pharmaceutical Ingredients (2007.Solanki).

One of the advantages is that proniosomes can be converted immediately into niosomes aerosol by hydration in hot water (2001a. Blazek), (2010. Sudhamani), (2007. Solanki.) and form multilamellar niosomes (2000. Hu and Rhodes.). Proniosomes act as a reservoir (carrier) and have been used for the targeted delivery to control the drug release and to achieve a prolong action. As proniosomes-derived niosomes have the ability to encapsulate both hydrophilic (within bilayer) and lipophilic (in central compartmental core) drug (2000.Hu and Rhodes.) so, verity of drug can be delivered to the targeted area (2010.Sudhamani).

The preparation of proniosomes and their evaluation was done by a number of authors (1998. Vora), (2000. Hu and Rhodes), (2001a and 2001 b. Blazek-welsh), (2001. Fang), (2005.Alsara), (2007. Gupta), (2007. Solanki), (2008. Azeem) and (2008. Abdelbary) for their different drug delivery system. Most of them used Proniosomes for the transdermal studies. Proniosomes are potentially very important because of their stability and large scale production. They were highly prepared for the transdermal application due to the non-toxicity and high penetration of non-ionic surfactant through skin (2010.Sankar. last conclusion). However, in future, they will be using for a verity of drug and target areas.

This is a post by Urwashi Sharad Naik on the paper:

Nanosized ethosmes bearing ketoprofen for improved transdermal delivery

by

Manish K. Chourasia, Lifeng Kang, Sui Yung Chan

Transdermal delivery of the drug provides excellent route of administration of the drug to enhance the oral absorption of the drug.  Our human skin contains the major barrier called stratum corneum layer which is a greatest challenge for transdermal delivery of drugs. Various approaches have been adopted to pass this major barrier such as micro needles, chemicals, surfactants, iontophoresis, chemicals and lipid based systems. The lipid based systems are of the best mechanism to carry out transdermal drug delivery as the lipids are biocompatible to our skin lipids. Conventional liposomes are used for transdermal drug delivery. However, these conventional liposomes are unable to cross the major stratum corneum barrier due to which the drug is unable to delivery deep inside the skin. These conventional liposomes have been modified by introduction of two novel carriers called as transfersomes and ethosomes. Transfersomes are ultradeformable lipid vesicles which consist of one layer of phospholipid and other layer of surfactants which allows them to squeeze through the stratum corneum layer and enhances the transdermal delivery of the drug. One the other hand, ethosomes are the vesicles contain higher concentration of the ethanol which acts as penetration enhancer allowing them to be more flexible than liposomes. The preparations of ethosomes are similar to liposomes but in liposomal preparation cholesterol and phospholipids are present but in ethosomes higher concentration of ethanol is present in place of cholesterol. As reported by Elsayed et al., ethosomes seems to be more superior than tansferosomes with respect to increase the permeability of entrapped ketotifen.

Ketotifen is non-steroidal anti-inflammatory drug. This drug have been tried to pass through other modes of transdermal delivery such as gels/patches which are available in the market. However, the drug delivery has been poorly observed previously. In this experiment, ketotifen have been entrapped in the ethosomal bilayer and the invitro and invivo transdermal delivery of this drug have been studied using varies techniques of characterization such as laser diffraction, zeta charger, HPLC (for drug entrapment), confocal laser scanning microscopy and micro column centrifugation. The in vivo studies were performed using the skin samples of female adult mice.

For in vitro studies, the experimental procedure was setup by placing the cellophone membrane dialysis tubing with both the ends sealed and suspended into a beaker containing PBS solution (pH 7.4)of 100 ml at 37 ± 1 ᵒC. The buffer of the solution was stirred at 45 mins intervals and sample was collected at 24,6,8,10,12,18 and 24 hr time intervals by replacing with equal quantities of fresh buffer and drug contain was analysed using HPLC. Different ethosomal formutions were evaluated for drug release and compared with hydroaloholic drug solutions.

For in vitro studies, the permeation was checked through diffusion cell system consisting of 16 channel peristaltic cassette pump, a circulating water bath, a fraction collector and flow through diffusion cells. Adult Chinese female skin was used in the experiment, the skin was thawed and hydrated with saline solution containing 1% v/v antibiotic antimitotic solution. For experiment the skin was immersed into water bath (60ᵒC) for 2 mins, peeled off and then stored at -80ᵒC.The receptor solution was pumped into the peristaltic cassette continuously through receptor compartment and drained into sample collection tubes. Sample collection was performed at various time intervals.

Penetration of ethosomes were confirmed using confocal laser scanning microscopy. The formulations were loaded with dye called fluorescent probe Rhodamine 123 insread of ketoprofen. Skin sample was mounted between the donar and the receiver compartment and either 1 ml of either hydroalcoholic probe solution was placed in the donar compartment and covered with paraflim to prevent contamination and evaporation at 37^oC. Skin was removed and washed after 4 hours and scanned at different increments through Z- axis of confocal laser scanning microscopy.

Drug quantitative studies was performed using HPLC using C18 column (Agilent, 5µm 4.0 x 250 mm) and using a mobile phase of phosphate buffer (pH 3.5) and acetonitrile in ratio of 50:50 at wavemenght 254 nm. The experiments were statistically performed using ANOVA. at p < 0.05 with mean ± standard deviation. The size of the vesicles were seems to be decrease with increase in concentration of alcohol contained. Higher concentration of ethanol confers net negative charges to the vesicular systems. As the keptoprofen is hydrophobic drug, it was expected to be encapsulated within the non-polar region of the bilayer as the bilayer amount increases the drug holding capacity also increases.

Entrapment efficiency of vesicles

The above table show that the entrapment efficiency of the vesicles increases with increase in phospholipid concentration even though keeping the concentration of the alcohol constant.

In vitro drug release through cellophane membrane shows that the hydroacoholic drug release was 3-4 hours slower than the drug release from the ethosomal preparation indicating that the drug diffusion in ethosomes is rate limiting step. The increase drug release may be due to increase in alcohol contain within the bilayer membrane.