Polymorphic transformation as a result of atovaquone incompatibility with selected excipients

Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, and hot-stage microscopy were employed to evaluate the drug–excipient compatibility of atovaquone with commonly used tablet excipients. The DSC curves of pure drug and excipients were compared with their physical mixtures. Microcrystalline cellulose, titanium dioxide, colloidal silica, ferric oxide, lactose monohydrate, and sodium starch glycolate were compatible, while magnesium stearate, polyethylene glycol (PEG) 8000, Poloxamer 188, and hydroxypropyl methyl cellulose (HPMC) E15 showed incompatibility with the drug. Heat–cool–heat analysis of the physical and the ground mixture of later three excipients showed polymorphic transformation of atovaquone form III to form I, which occurred via amorphization with HPMC E15 and through solubilization mechanism with remaining two excipients. These outcomes were further supported by hot-stage microscopy. Results of milling experiments revealed a milling time-dependent polymorphic transformation and solubilization with HPMC E15 and PEG 8000, respectively. This study highlights the importance of compatibility assessment for selection of excipients in specific unit operations such as milling and grinding.     

Drug-excipient compatibility studies by physico-chemical techniques; The case of Atenolol

We apply a range of techniques (thermal methods, microscopy, X-ray diffraction, IR spectroscopy) to characterize a drug (atenolol), several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©) and drug-excipients mixtures either as prepared, annealed, and exposed to moisture. We compare the data of the mixtures with those computed from a weighted average of similarly treated pure compounds to find evidence of drug properties modified by the interaction with the excipient. We find that thermal response is by far the most sensitive indicator of interaction while IR is the least sensitive one. Avicel© has essentially no interaction with atenolol, while MGST modifies significantly only the thermal response of the drug in the MGST-rich mixtures. PVP interacts strongly with atenolol, and this interaction appears to be mediated by the substantial amount of hydration water the excipient brings in its mixtures with a water-free drug.     

Application of thermal analysis in study of binary mixtures with metformin

Thermal analysis is an essential analytical tool in development of new formulations as well as to study the interaction between drugs and excipients. This work aims to investigate the possible interactions between metformin and excipients as microcrystalline cellulose (Microcel MC101®), starch sodium glycolate (Explosol®), sodium croscarmellose (Explosel®), PVP K30, magnesium stearate, starch and lactose, usually employed in pharmaceutical products. TG, DSC and DTA techniques were used for the thermal characterization to track if the thermal properties of the drug substance were modified in the mixture. Disregard of the starch and lactose systems, no changes in thermal behavior of mixtures were found. Thermogravimetric studies (TG) of metformin and its binary mixtures showed different thermal behavior.     

Drug-excipient compatibility studies in binary and ternary mixtures by physico-chemical techniques

This work is part of a systematic study undertaken to find and optimize a general method of detecting the drug-excipient interactions, with the aim of predicting rapidly and inexpensively the long term stability of a pharmaceutical product and speed up its marketing. Here, in particular, the compatibility of haloperidol with several excipients (PVP, magnesium stearate and α-lactose) in binary and ternary mixtures, both as prepared and ball-milled, has been assessed by thermal methods, electron microscopy, IR spectroscopy and X-ray diffraction. The differences between the experimental behaviour of the systems and that expected as weighted average of similarly treated pure components are interaction indicators. The DSC has proven to be, among the selected analytical techniques, the most sensitive and specific in assessing the compatibility. A strong interaction has been observed between PVP and haloperidol. It is favoured by the mechanical stress and is more evident in the composition 20:80. On the contrary, α-lactose and magnesium stearate were found to be compatible with the drug.     

Compatibility study between chlorpropamide and excipients in their physical mixtures

Chlorpropamide ((4-chloro-N-(propylamino)-carbonyl)-benzenesulfonamide) belongs to compounds having sulfonylurea group and is widely used as an oral antidiabetic agent. In this work differential scanning calorimetry (DSC) was used during pre-formulation of chlorpropamide tablets to determine the drug-excipients compatibility. The DSC curves of chlorpropamide and binary mixtures with excipients (sodium croscarmellose, sodium lauryl sulfate, microcrystalline cellulose, magnesium stearate and calcium carbonate) showed that chlorpropamide exhibited interaction with magnesium stearate and sodium lauryl sulfate. The binary mixtures of chlorpropamide–magnesium stearate presented a single endothermic process at 96–108 °C and chlorpropamide–sodium lauryl sulfate showed a wide endotherm at 99–120 °C.     

Thermotropic phase behaviour of mixed liposomes of archaeal diether and conventional diester lipids

During preformulation studies of pharmaceutical solid dosage forms, thermal analysis techniques are very useful to detect physical or chemical incompatibilities between the drug and adjuvants of interest that might interfere with efficacy and safety of the final drug product. Differential scanning calorimetry (DSC) and thermogravimetry (TG) are useful tools for this purpose. The aim of this study was to investigate the thermoanalytical behavior of olanzapine (OLZ) when mixed with several excipients commonly used in solid dosage forms such as microcrystalline cellulose, croscarmellose, dicalcium phosphate dihydrate (DCPD), lactose, magnesium stearate, and povidone. Following DSC and TG analyses, powder X-ray diffraction tests were carried out. Thermoanalytical methods showed evidence of interaction between OLZ and magnesium stearate, lactose, and povidone. These results can be useful during the selection of excipients for pharmaceutical formulation development.     

Design and in vitro evaluation of zidovudine oral controlled release tablets prepared using hydroxypropyl methylcellulose

Oral controlled release matrix tablets of zidovudine were prepared using different proportions and different viscosity grades of hydroxypropyl methylcellulose. The effect of various formulation factors like polymer proportion, polymer viscosity and compression force on the in vitro release of drug were studied. In vitro release studies were carried out using United States Pharmacopeia (USP) type 1 apparatus (basket method) in 900 ml of pH 6.8 phosphate buffer at 100 rpm. The release kinetics were analyzed using Zero-order model equation, Higuchi's square-root equation and Ritger-Peppas' empirical equation. Compatibility of drug with various formulations excipients used was studied. In vitro release studies revealed that the release rate decreased with increase in polymer proportion and viscosity grade. Increase in compression force was found to decrease the rate of drug release. Matrix tablets containing 10% hydroxypropyl methylcellulose (HPMC) 4000 cps were found to show a good initial drug release of 21% in the first hour and extended the release upto 16 h. Matrix tablets containing 20% HPMC 4000 cps and 10% HPMC 15000 cps showed a first hour release of 18% and extended the release upto 20 h. Mathematical analysis of the release kinetics indicated that the nature of drug release from the matrix tablets followed non-Fickian or anomalous release. No incompatibility was observed between the drug and excipients used in the formulation of matrix tablets. The developed controlled release matrix tablets of zidovudine, with good initial release (17-25% in first hour) and which extend the release upto 16-20 h, can overcome the disadvantages of conventional tablets of zidovudine.     

Evaluation of compatibility of tablet excipients and novel synthesized polymer with lamivudine

The present study describes compatibility of anti-HIV drug lamivudine with various selected excipients and a novel synthesized polymer, for the development of its controlled release formulation. Differential scanning calorimetry (DSC), isothermal stability study (ISS) and Fourier transform infrared (FT-IR) spectral analysis were performed to access the compatibility. The compatibility study was performed with various common excipients like spray dried lactose, polyvinyl pyrrolidine K-30, magnesium stearate, talc and a novel synthesized polymer cross-linked sago starch with lamivudine.     

Study of the critical points in lobenzarit disodium hydrophilic matrices for controlled drug delivery

Percolation theory is a multidisciplinary theory that studies chaotic systems. It has been applied in the pharmaceutical field since 1987. The application of this theory to study the release and hydration rate of hydrophilic matrices allowed for first time to explain the changes in release and hydration kinetic of swellable matrices type controlled delivery systems. The objective of the present paper is to estimate the percolation threshold of HPMC K4M in matrices of lobenzarit disodium and to apply the obtained result to the design of hydrophilic matrices for the controlled delivery of this drug. The materials used to prepare the tablets were Lobenzarit disodium (LBD) and HPMC of viscosity grade K4M. The drug mean particle size was 42+/-0.61 mum and the polymer was sieved and 150-200 microm granulometric fraction was selected. The formulations studied were prepared with different excipient contents in the range of 10-80% w/w. Dissolution studies were carried out using the paddle method and the water uptake measurements were performed using a modified Enslin apparatus. In order to estimate the percolation threshold, the behaviour of the kinetic parameters with respect to the volumetric fraction of each component at time zero, was studied. According to percolation theory, the critical points observed in dissolution and water uptake studies are attributed to the existence of an excipient percolation threshold. This threshold was situated between (18.58 to 24.33% v/v of HPMC). Therefore, the LBD-HPMC K4M matrices with a relative HPMC particle size of should be formulated with an excipient content above 24.33% v/v of HPMC, to obtain a control of the drug release from these systems.     

Sibutramine hydrochloride monohydrate

In the present work, the thermal decomposition of sibutramine hydrochloride monohydrate (SBT) (an appetite suppressant agent) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry (TG/DTG). Solid-state characterization was carried out by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). Isothermal and non-isothermal methods were employed to determine the kinetic data of decomposition process. From isothermal experiments, activation energy (Ea) can be obtained from slope of ln t versus 1/T, and the value obtained was 96.06 and 101.43 kJ mol⁻¹ in N₂ and air atmospheres, respectively. For non-isothermal method Ea can be obtained from plot of logarithms of heating rates, as a function of inverse of temperature, resulting in a value of 96.56 and 98.22 kJ mol⁻¹ in N₂ and air atmospheres, respectively. The compatibilities of several commonly used pharmaceutical excipients (microcrystalline cellulose, magnesium stearate, colloidal silicon dioxide, lactose monohydrate) and empty hard-gelatin capsules with SBT were evaluated using DSC. The 1:1 physical mixtures of these excipients with SBT showed physical interaction of the drug with magnesium stearate. On the other hand, DRIFT results did not evidence any chemical modifications.     

Compatibility study of quetiapine fumarate with widely used sustained release excipients

The drug-excipient compatibility study of quetiapine fumarate, with widely used sustained release excipients, was carried out employing differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The selected excipients were HPMC K100M, sodium alginate, xanthan gum, Eudragit RSPO, hydrogenated castor oil, carnauba wax, and PEO WSR 303. Equal proportion of drug and excipients was utilized in the interaction study. FT-IR spectra indicated the absence of interaction between drug and excipients. The DSC curve showed a sharp endothermic melting peak at 173.26 °C for quetiapine fumarate. Post melting interaction was observed for carnauba wax, Eudragit RSPO, and hydrogenated castor oil probably due to solubilization of drug in the melted excipient. No interaction was observed for other excipients. The physical mixtures stored at 30 ± 2 °C/65 ± 5% RH did not show any significant degradation of the drug. The concept of systemically conducted preformulation studies will facilitate dossier submission to the drug control authority.     

Physicochemical characterization of dipeptidyl peptidase-4 inhibitor alogliptin in physical mixtures with excipients

Alogliptin (ALG) is a hypoglycemic drug used in diabetes which inhibits the enzyme dipeptidyl peptidase-4 (DPP-4), preventing the degradation of incretins, stimulating insulin secretion. The physicochemical characteristics of ALG were evaluated by differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy equipped with energy-dispersive X-ray spectrometer (SEM/EDS). The compatibility studies were carried out between ALG and excipients (physical mixtures, 1:1) using DSC, TG, diffuse reflectance Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD) and hot-stage microscopy. ALG presented purity near to 99%, melted in the range of 179.4–187.2 °C, followed by decomposition which started in 198.0 °C. SEM/EMS analysis of ALG presented irregular crystals and traces of impurities as copper and lead. DSC investigations obtained by physical mixtures showed minor alterations in the melting ranges of ALG with mannitol, magnesium stearate and commercial tablets. Solubilization of ALG in the fused excipient was observed by hot-stage microscopy between mannitol and ALG, and in tablets. The interaction observed in the mixture with magnesium stearate is due to the melting of the excipient and drug separately, first the excipient and then the drug. FTIR showed additional bands related to the excipients. XRPD proved that ALG has a crystal form and no alterations in the ALG profile were observed after the mixtures. ALG was compatible with all excipients tested. These results were important to understand the characteristics, stability and compatibility of the drug, and proved to be useful in preformulation studies.

     

tudy on compatibility of imatinib mesylate with pharmaceutical excipients

Differential scanning calorimetry and thermogravimetric analysis with the support of X-ray powder diffraction and infrared spectroscopy were used as screening techniques for the compatibility testing of imatinib mesylate, with following excipients: magnesium stearate, polyvinylpyrrolidone, microcrystalline cellulose. In order to maximize the probability of interactions 1:1 (by mass) drug: excipient binary mixtures were analysed and compared to individual components. Additionally an influence of storage at temperatures of 25 and 40°C on physico-chemical stability on drug – excipient binary mixtures was investigated. The largest visible changes were observed in the DSC curves of imatinib mesylate – magnesium stearate mixtures.     

Compatibility studies of aceclofenac with retard tablet excipients by means of thermal and FT-IR spectroscopic methods

The compatibility of aceclofenac with various tableting excipients was investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The excipients applied in the direct pressing retard tablets were Carbopol 940, hydroxypropyl-methyl-cellulose, microcrystalline cellulose, Aerosil 200 and magnesium stearate. The ingredients alone and their 1:1 (w/w) binary mixtures were investigated before and after accelerated storage. An interaction was observed only between aceclofenac and magnesium stearate. The DSC and FT-IR examinations indicated formation of the magnesium salt of aceclofenac. For the other mixtures, there was no incompatibility between the components.     

Risperidone/Randomly Methylated β-Cyclodextrin Inclusion Complex—Compatibility Study with Pharmaceutical Excipients

Risperidone (RSP) is an atypical antipsychotic drug used in treating schizophrenia, behavioral, and psychological symptoms of dementia and irritability associated with autism. The drug substance is practically insoluble in water and exhibits high lipophilicity. It also presents incompatibilities with pharmaceutical excipients such as magnesium stearate, lactose, and cellulose microcrystalline. RSP encapsulation by randomly methylated β-cyclodextrin (RM-β-CD) was performed in order to enhance drug solubility and stability and improve its biopharmaceutical profile. The inclusion complex formation was evaluated using thermal methods, powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier transform infrared (UATR-FTIR), UV spectroscopy, and saturation solubility studies. The 1:1 stoichiometry ratio and the apparent stability constant of the inclusion complex were determined by means of the phase solubility method. The compatibility between the supramolecular adduct and pharmaceutical excipients starch, anhydrous lactose, magnesium stearate, and cellulose microcrystalline was studied employing thermoanalytical tools (TG-thermogravimetry/DTG-derivative thermogravimetry/HF-heat flow) and spectroscopic techniques (UATR-FTIR, PXRD). The compatibility study reveals that there are no interactions between the supramolecular adduct with starch, magnesium stearate, and cellulose microcrystalline, while incompatibility with anhydrous lactose is observed even under ambient conditions. The supramolecular adduct of RSP with RM-β-CD represents a valuable candidate for further research in developing new formulations with enhanced bioavailability and stability, and the results of this study allow a pertinent selection of three excipients that can be incorporated in solid dosage forms.     

Compatibility study of the acetylsalicylic acid with different solid dosage forms excipients

This study is part of a research project aimed to find and optimize methods by which drug-excipient compatibility can be reliably and quickly assessed. The objective of the present study was to evaluate the compatibility of the acetylsalicylic acid (ASA), an non-steroidal anti-inflammatory drug, with pharmaceutical excipients of common use including diluents, binders, disintegrants, lubricants and solubilising agents. In order to investigate the possible interactions between ASA and eleven excipients differential scanning calorimetry (DSC) and thermogravimetry/derivative thermogravimetry analysis completed by Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction were used for compatibility study. The DSC has proven to be, among the selected analytical techniques, the most sensitive and specific in assessing the compatibility. The samples, as physical mixtures, were prepared by mixing the analyte and excipients in a proportion of 1:1 (w:w). On the basis of thermal results (especially DSC), confirmed by FT-IR and X-ray analysis, a possible chemical interaction was found between the ASA with polyvinylpyrrolidone K30 (PVP) and magnesium stearate, respectively a possible physical interaction with colloidal silicon dioxide and stearic acid (Ac. St.).     

Application of DSC, IST, and FTIR study in the compatibility testing of nateglinide with different pharmaceutical excipients

Experiments were done to assess the compatibility of nateglinide (NTG) with selected excipients in the development of immediate release tablets of NTG by thermal and isothermal stress testing (IST) techniques. To evaluate the drug excipient compatibility, different techniques such as differential scanning calorimetric (DSC) study, infrared (IR) spectrophotometric study, and IST were adopted. The results of DSC study showed that magnesium stearate exhibited some interaction with NTG. However, the results of IR and IST studies showed that all the excipients used in the formula were compatible with NTG. The optimized formulation developed using the compatible excipients were found to be stable after 3 months of accelerated stability studies (40 ± 2 °C and 75 ± 5% RH). Overall, compatibility of excipients with NTG was successfully evaluated using the combination of thermal and IST methods and the formulations developed using the compatible excipients was found to be stable.     

FTIR, XRD, and DSC analysis of the rosemary extract effect on polyethylene structure and biodegradability

The purpose of this research study was evaluation of the utility of two common multivariate techniques, agglomerative cluster analysis (CA) and principal component analysis (PCA), as supplementary means of detecting incompatibilities, which can occur between active pharmaceutical ingredients and excipients at the preformulation stage of a solid dosage form. For the detection of incompatibilities between atenolol (beta blocker) and selected excipients (mannitol, lactose, starch, methylcellulose, β-cyclodextrin, meglumine, chitosan, polyvinylpyrrolidone and magnesium stearate), the thermogravimetry (TG), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were chosen. The results have shown that compatibility between atenolol and an excipient can be identified in a CA dendrogram by two large clusters, from which one groups an excipient and physical mixtures with a high concentration of the excipient. Another cluster encompasses atenolol and mixtures with a high content of the drug. In the PCA plot, all samples are located along the first principal component axis (PC1), beginning from a single component located with the most negative PC1 value, through mixtures with gradually varying concentration of both ingredients, till the second component located close to the most positive PC1 values. The results have shown that CA and PCA fulfil their role as supporting techniques in the interpretation of the data acquired from the TG curves, and the obtained data are compatible with the results of DSC and FTIR analyses.     

Controlled release of atenolol from freeze/thawed poly(vinyl alcohol) hydrogel

Physically crosslinked polymeric films containing atenolol drug were formulated and the release of the drug was evaluated with view to investigate the feasibility of these films as drug delivery systems. Freezing and thawing process for PVA was used to prepare a controlled release device for atenolol drug. The process included incorporation of the drug into PVA film during the freezing and thawing process. The PVA has used a molecular weight of 125 k and degree of saponification of 98. Various amounts of the atenolol drug were incorporated into the freeze/thawed PVA. The in vitro release behavior of atenolol from these films was investigated. The drug release profiles from the polymeric formulations indicated initial high rate of release followed by slow rate of the release. The release of atenolol increased with increasing drug concentration in the film. The results showed the feasibility of the use of freezing and thawing technique to control the release of atenolol drug from PVA.