Research Article ISSN: 0974-6943 Rohit Pawaret al. / Journal of Pharmacy Research 2012,5(5), Available online through http://jprsolutions.info Solubility enhancement of pioglitazone by spray drying techniques using hydrophilic carriers Rohit Pawar 1, Swapnila V Shinde (Vanshiv) 2*, Siddheshwar Deshmukh 3. 1,2,3 Department of Pharmaceutics, Sinhgad Institute of Pharmacy, Narhe, Pune- 411 041, India. *Corresponding author. Swapnila V. Shinde (Vanshiv) STES s Sinhgad Institute of Pharmacy, S. No. 45/1, Off Westerly Bypass, Mumbai- Pune Expressway, STES Narhe Campus (Annex.), Narhe, Pune- 411 041 (M.S.) India Received on:11-01-2012; Revised on: 17-02-2012; Accepted on:19-04-2012 ABSTRACT The formulation of hydrophobic drugs for oral drug delivery is challenging due to poor solubility, poor dissolution and poor wetting of these drugs. Consequently, the aim of this study was to improve the dissolution of a model poorly water soluble drug, Pioglitazone (PIO). Microparticles containing PIO were produced by spray drying technology in the presence of hydrophilic carriers. Poloxamer 407 (Polo), ß-Cyclodextrin (ß-CD) was chosen as the hydrophilic carriers to improve drug particle wettability and hence the dissolution rate. The prepared formulations were evaluated for in vitro dissolution and intrinsic solubility. In addition, the produced drug particles were characterised by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (X-RD) studies. DSC data showed shifting of the melting peak of the drug towards lower melting temperature in the prepared particles, indicating possibility of drug /polymer interaction. The results of the dissolution studies of spray dried PIO and spray dried PIO/ Polo, PIO/Polo/ ß-CD, PIO/ß-CD particles showed significantly increased percentage drug release compared to control (Pure PIO). X-RD results demonstrated that spray drying reduced drug crystallinity. Consequently, it is believed that spray drying of PIO is a useful tool to improve wettability, solubility and hence the dissolution behaviour of poorly water soluble drugs. Keywords:Pioglitazone, Spray drying, Poloxamer 407, ß-Cyclodextrin. INTRODUCTION The oral route remains the preferred route of drug administration due to its convenience, good patient compliance and low medicine production costs. In order for a drug to be absorbed into the systemic circulation following oral administration, the drug must be dissolved in the gastric fluids. For hydrophobic drugs, it is the dissolution process which acts as the rate-controlling step and, therefore, determines the rate and degree of absorption. Consequently, many hydrophobic drugs show erratic and incomplete absorption from the gastrointestinal tract of animals and humans, which may lead to therapeutic failure 1. Thus, one of the major challenges to drug development today is poor solubility, as an estimated 40% of all newly developed drugs are poorly soluble or insoluble in water. As a result, much research has been conducted into methods of improving drug solubility and dissolution rates to increase the oral bioavailability of hydrophobic drugs 1,2. Various techniques such as melt adsorption, supercritical fluid processes, and many polymeric carriers such as polyvinyl pyrollidone (PVP) and polyethylene glycol (PEG) and silica carrier have been attempted to load poorly water soluble drugs in nano- or micro-crystals and amorphous state to improve their dissolution. Manipulation of the solid state by decreasing crystallinity of drug substances through formation of solid dispersion is one of the methods used for promoting drug dissolution. The solid dispersion technique has often proved to be the most successful in improving the dissolution and bioavailability of poorly water soluble active pharmaceutical ingredients because it is simple, economic, and advantageous technique. The concept of solid dispersion covers a wide range of systems 1. The enhancement in the dissolution rate is obtained by one or a combination of the following mechanisms: eutectic formation, increased surface area of the drug due to precipitation in the carrier, formation of true solid solution, improved wettability (due to close contact with a hydrophilic carrier), drug precipitation as a metastable crystalline form or a decrease in substance crystallinity. The type of solid dispersion formed depends on both the carrier-drug combination and the method of manufacture 3. Spray drying is one such technique of preparing solid dispersion and is widely used as an alternative to milling to reduce particle size. It has the advantage of being capable of designing the features, such as improved particle wetting by adding small amount of surfactants 1. Pioglitazone was chosen as a model hydrophobic drug. PIO 5-({4-[2-(5- ethylpyridin-2-yl) ethoxy]phenyl}methyl)-1,3-thiazolidine-2,4-dione, is safe and antidiabetic drug being widely used in market 8. The drug is used to treat type II diabetes mellitus. It has low aqueous solubility and hence poor dissolution. The present work was conducted to improve the dissolution of PIO using spray drying techniques. Poloxamer 407 (which is non-ionic amphiphilic surfactant and tri-block copolymer of polyoxyethylene- polyoxypropylenepolyoxyethylene).ß- Cyclodextrin (ß-CD) is cyclic malto oligosaccharides in which the glucose units are linked by a- 1, 4 glycoside bonds & ß- CD was used in formulations in an attempt to increase drug solubility and hence drug dissolution 6, 7. MATERIALS AND METHODS Materials Pioglitazone was received a gift sample from Dr. Reddy s Laboratories Ltd, Hyderabad, India. Poloxamer 407 (Pluronic F-127) was received a gift sample from BASF, Mumbai India. ß- Cyclodextrin gift sample (Thomas Beker Mumbai, India). All other chemicals and solvents used were of analytical grade. Preparation of Microparticles Preparation of physical mixture The physical mixtures of PIO with Polo & ß- CD (1:1, 1:1, molar ratios) were prepared by light mixing the two components in a mortar. Then it was passed through a 60 mess sieve and stored in desiccators until used 3. Preparation of Microparticles by spray drying Spray dried particles consisted of PIO/ßCD (1:1 (w/w) ratio), PIO/Polo (1:1 (w/w) ratio) & PIO/Polo/ßCD were prepared by dissolving the drug or drug/ polymer mixture in methanol/water (40:60 (v/v) ratio) solution. The solution was spray dried using lab Spray Dryer B-290- (Buchi, Switzerland) at a pump rate of 35%, an air flow rate of 600 L/h, aspirator level at 100%, inlet temperature at 97 ±2 C and outlet temperature at 78 ±1 C. The formed microparticles were separated using cyclone separator, collected and stored in a desiccators at ambient temperature until ready to be used 3.
Rohit Pawaret al. / Journal of Pharmacy Research 2012,5(5), EVALUATION OF MICROPARTICLES Stability Studies Phase solubility study The stability of solid dispersions was checked by storing the tightly sealed Phase solubility studies were carried out at room temperature in triplicates vials at room temperature and 40ºC, 75% RH. Periodically samples were according to the method reported by higuchi & Connors. Excess amount of removed and analyzed for their stability 8. PIO was added to distilled water containing various concentrations of ß CD (0.002-0.01) in a series of Stoppard conical flasks and shaken for 24 hr on a RESULTS AND DISCUSSION rotatory flask shaker. The suspension were filtered through Whatman filter paper and assayed for PIO using UV/Vis spectrophotometer at 269.5 nm against blank prepared using same concentration of ß CD in distilled water. The association constant (Ka) was calculated from the slope of the linear portion of the phase solubility diagram 6. According to equation (1). Ka = Slope Intercept (1-slope) Saturation Solubility Study Saturation solubility study was done to determine the excess of solubility of drug with different hydrophilic carriers. Excess amount of drug (and drug with each of complexing agent) was added in 100ml of distilled water. The mixture was equilibrate for 24 hrs at room temperature. It was then filtered through Whatman filter No.45. Analysed by UV-Spectrophotometrically at 269.5 nm 4. Determination of percentage yield and Drug content The percentage yield of each formulation was determined according to the total recoverable final weight of particles (prepared by spray drying) and the total original weight of PIO & polymer. Samples (50 mg) were triturated with 10 ml of water. Allowed to stand for 10 min with occasional swirling and methanol was added to produce 100 ml. After suitable dilution, samples were measured at 269.5 nm. Drug content was determined from standard plot 4. Differential scanning calorimetry (DSC) A DSC study was carried out to detect possible polymorphic transition during the crystallization process. DSC measurements were performed on a DSC 60 (Shimadzu Corporation, Japan) model, differential scanning calorimeter with a thermal analyzer. All accurately weighed samples (about 2mg of PIO) were hermetically sealed in aluminium pans and heated at constant rate at 10 0 C/min over a temperature range of 25 250 0 C. An inert atmosphere was maintained by purging nitrogen gas at flow rate of 20 ml/mm 5. Fourier transform infrared (FTIR) spectroscopy The FTIR spectral measurements were taken at ambient temperature using a JASCO, Model 4100 series. Samples of pure PIO and solid dispersions were dispersed in KBr powder. The scanning range was 4000 to 400cm -1. FTIR spectra were obtained by powder diffuse reflectance on FTIR spectrophotometer 1. X-ray analysis X-Ray powder diffraction patterns were obtained at room temperature using a Philips X Pert MPD diffractometer, with Cu as anode material and graphite monochromator, operated at a voltage of 40 ma, 45 kv. The samples were analysed in the 2? angle range of 2? - 65? and The process parameters used were set as scan step size of 0.025 (2?) & scan step time of 1.25s 1,2. In vitro dissolution studies The dissolution studies were performed using United State Pharmacopoeia type II dissolution test apparatus (Electro Lab). Sample equivalent to drug of about 50 mg were placed in the dissolution vessel containing 900 ml of water maintained at 37 C ±0.5 C and stirred at 100 rpm. PIO raw material was used as control. Samples were withdrawn of 10 ml at an interval of 10min, 20min up to 60 min. filtered samples, using 0.45µm membrane filter, were collected periodically and replaced with a fresh dissolution medium. The concentration of PIO released was determined spectrophotometrically at 269.5 nm on a UV/Vis spectrophotometer (JASCO Double Beam Scanning) 4,5. Fig: 1 Phase solubility study for ß Cyclodextrin Phase solubility study Phase solubility profile for the complex formation between PIO and ß-CD at 37 o c. The solubility of PIO increased in a linear fashion of ß-CD concentration and followed an A L type system according to Higuchi and Conners 8 showing that soluble complexes were formed and no precipitation was observed over the entire concentration range studied. This linear host-guest correlation with a slope less than 1 suggested the formation of first order soluble complexes. The Ka value is a useful index to estimate the degree of binding strength of the complex and changes of physicochemical properties of the guest in the complex. Change in the Ka value depends on the change of environmental factors such as dilution temperature, ph and additives. Phase solubility analysis indicated the formation of first order soluble complexes. The stability constant 371.08 M -1 obtained was within the range of 200-5000 M -1, which is considered by various authors as adequate for the formation of inclusion complexes, which may contribute to improving solubility of poorly water soluble drugs(fig.1). Saturation Solubility Study Saturation solubility study was done to determine the excess of solubility of drug with different hydrophilic carriers. Solubility of pure drug, physical mixture (PM), and spray dried product was shown in Table no.1&2 Table 1. Saturation solubility study for Physical Mixture. Sr. No. Parameter Solubility % increase Increase in % yield % Drug in in solubility Content mcg/ml solubility by folds 1 Pure Drug 5.76 - - - - 2 Pio+â CD 8.6 161.6 0.616 80.14 91.48 3 Pio+â CD+Polo 10.54 182.98 0.83 94.97 89.82 4 Pio+Polo 15.04 261.11 1.61 96.52 94.79 Table. 2. Saturation solubility study for Spray Drying: Sr. No. Parameter Solubility % increase Increase in in mcg/ml in solubility solubility by folds 1 Pure Drug 5.76 - - 2 Pio+ß CD 17.36 301.38 2.01 3 Pio+ß CD+Polo 20.59 357.46 2.57 4 Pio+Polo 24.05 465.18 3.18
Rohit Pawaret al. / Journal of Pharmacy Research 2012,5(5), Percentage yields and drug contents For physical mixture formulation the percentage yields from PIO/ß-CD, PIO/Polo & PIO/CD/Polo were 80.14 %, 96.52 % & 94.97 %, respectively & for spray dried drug formulations, the collected powders were white and fairly free-flowing. The percentage yields from PIO/ß-CD, PIO/Polo & PIO/ ß-CD/Polo were 19.4 %, 19.6 % & 41.97 %, respectively. Such small yield for the drug alone considers being acceptable for small scale. And for drug content of Physical mixture from PIO/ß-CD, PIO/Polo & PIO/CD/Polo were 91.48 %, 94.79 % & 89.82 %, respectively & for spray dried drug formulations, PIO/ß-CD, PIO/Polo & PIO/ßCD/Polo were 94.36 %, 91.52 % & 96.97 %, respectively (Table No.1). Fourier-transform infrared spectroscopy (FTIR) Fourier transform infrared spectra of Pure Drug & Spray dried of PIO with Polo and ß- CD are shown in (Fig. 4,5&6 ). The spectra of pure drug showed peaks at 3310.23cm-1(N-H stretch), 1649.70cm-1(C=O stretch), 1575.30cm- 1 (N-H bending), 1507-08cm-1 (C=C stretch), 751.38cm-1(aromatic stretch). PIO In Vitro Dissolution Study Were studied using an USP XXIII six station dissolution rate test apparatus (Electro Lab). Paddle stirrer at a speed of 100 rpm and temperature of 37 0 ± 2 0 C were used in each test. Drug or solid dispersion of drug 50 mg of PIO was used in each dissolution rate test. Samples of dissolution medium i.e., Water (10ml) were withdrawn through a filter (0.45 µ) at different time intervals, suitably diluted, and assayed for PIO. The results are given in Table No- 3. Figure 2 & 3 Shows the release pattern of all mixture compared with pure drug. Fig 4: FTIR of Pioglitazone Fig.2. % Cumulative Release of Physical Mixture Fig 5: FTIR for Physical Mixture Fig. 3. % Cumulative release of Spray drying Table. 3. % Cumulative Release of Drug & Mixtures Sr. No. Parameters % Cumulative release 1 Pure Drug 8.18 2 Physical Mixture a) PIO+ß CD 61.46 b) PIO+ß CD+Polo 33.24 c) PIO+Polo 57.49 3 Spray Drying a) PIO+ß CD 69.65 b) PIO+ß CD+Polo 38.78 c) PIO+Polo 68.25 Fig 6: FITR for Spray Drying Differential Scanning Calorimetry (DSC) DSC thermograms are obtained for PIO, Polo, ß- CD are displayed in Fig.7&8 Pure PIO has shown well defined endothermic peak at 205 0 C. Corresponding to the melting point of crystalline drug. Likewise the excipients have shown endothermic peaks at 56 0 C and 140 0 C for Polo and â- CD, respectively, representing the melting points. However in the thermogram of the spray dried solid dispersion, the endotherm peak of drug disappeared and instead new peak was observed at 57 0 C & 76 0 C with Polo & â CD respec-
Rohit Pawaret al. / Journal of Pharmacy Research 2012,5(5), Fig 7:- A) PIO, B) Physical Mixture- PIO+Polo, C) Physical Mixture- PIO+ ß CD Fig 8: - A) PIO B) Spray Dried- PIO+Polo C) Spray Dried- PIO+ ß CD Fig 9- X-RD of 1) PIO 2) Physical Mixture: - PIO+ ß CD 3) Physical Mixture:- PIO + Polo 4)Physical Mixture:-PIO + Polo + ß CD
Rohit Pawaret al. / Journal of Pharmacy Research 2012,5(5), Fig.10: X-RD of 1) PIO 2) Polo 3) Spray Dried: - PIO + Polo 3) Spray Dried:- PIO + Polo + ß CD tively. However the endothermic peaks of Polo and â- CD remains same. The significant reduction in the melting point of the PIO can be attributed to the morphological conversion of PIO from crystalline to amorphous form. X-ray diffractometry (XRD) The XRD patterns of the PIO, Polo and ß- CD spray dried are shown in (Fig.9&10). It has been observed that the diffraction patterns of the solid dispersions are somewhat diffused compared to diffraction patterns of PIO. It also indicates that the crystallinity of the solid dispersions are less than that of the PIO. Stability study The best formulation was subjected to accelerated stability studies as per the ICH guidelines. There were no changes in appearances and percentage drug content of SDs stored at different temperature at 40±2 o C/ 75 % ± 5% RH. All the parameters were within the limit after three months. REFERENCES 1. Elkordy A.A., Essa E.A., Dissolution of ibuprofen from spray dried And spray chilled particles, Pak. J. Pharm. Sci, Vol.23, No.3, July 2010,Page No. 284-290. 2. Dixit M., Kini G A., Preparation and characterization of spray dried microparticle and spray chilled particle of mefenamic acid by spray drying method, International Journal of Pharmaceutical Sciences Review and Research, Vol. 5, Issue 2, Nov. Dec. 2010, Page No. 28-33 3. Shah S.S., Pandya S.J., Enhancement of solubility and physical characterization of nimodipineâ-cyclodextrin inclusion complexes, Journal of Pharmacy Research, Vol.2.Issue 3.March 2009,Page No.432-436. 4. Prasada Rao C.V., Nagabhushanam M.V., Enhancement of Dissolution Rate of Poorly Soluble Drug Mefenamic Acid by Solid Dispersion, Research Journal of Pharmaceutical, Biological and Chemical Sciences, Vol. 2, Issue 3, Jul Sep 2011, Page No. 1025-1035. 5. Singh M.C., Sayyad A.B., Review on various techniques of solubility enhancement of poorly soluble drugs with special emphasis on solid dispersion, Journal of Pharmacy Research, Vol. 3(10), 2010, Page No. 2494-2501. 6. Beloshe S. P., Chaugule D.D., Effect of Method of preparation on Pioglitazone HCL- ß CD inclusion complexes, Asian journal of pharmaceutics, April-June 2010, Page No. 168-172. 7. Gajare P., Patil C., Effect of hydrophilic polymers on Pioglitazone complexation with hydroxypropyl-ß-cyclodextrin, Digest Journal of Nanomaterials and Biostructures, Vol-4 (4), Dec.- 2009, Page No.- 891-897. 8. Kulthe V.V., Chaudhari P.D., Solubility Enhancement of Etoricoxib by Solid Dispersions Prepared by Spray Drying Technique, Indian Journal of Pharmaceutical Education and Research, Vol 45 (3), Jul- Sept, 2011, Page No.-248-258. 9. J Peeters, P.Neeskens, JP.Tollenaere, P.VanRemoortere. Various application of cyclodextrin in pharmaceutical industry. Ind. J Pharm. Sci., 91, Page No.-1414-1422. 10. Derle D.V, Shinde S.B, Gujar K.N. Inclusion complexation of Roxithromycin with ß- cyclodextrin. Int. J. Pharma. Excip., 2003:Page No.-95-100. Source of support: Nil, Conflict of interest: None Declared