Combining eugenol and dihydroeugenol with a piperazine moiety to create new antimicrobial agents that are effective against resistant species.

Historically, the piperazine moiety has been demonstrated to possess pharmacophoric properties, and has subsequently been incorporated in many drugs that have antitumor, antimalarial, antiviral, antibacterial and antifungal properties. Derivatives of eugenol and dihydroeugenol have also been reported as being bioactive compounds. This study reports the synthesis of a range of eugenol/dihydroeugenol - piperazine derivatives which have been tested as antimicrobial compounds against Gram positive, Gram negative and rapid-growing mycobacteria (RGM). The rationale employed in the design of the structural pattern of these new derivatives, provides useful insights into the structure-activity relationships (SAR) of the series. Antimicrobial activity tests were extremely encouraging, with the majority of the synthesised compounds being more active than eugenol and dihydroeugenol starting materials. The antimicrobial potential was most notable against the Gram-negative species K. pneumoniae and P. aeruginosa, but there was also significant performance against the Gram-positive strains S. epidermidis and S. aureus and the Rapidly Growing Mycobacteria (RGM) strains tested. Tests using the synthesised compounds against multidrug-resistance clinical (MDR) isolates also showed high activity. The biofilm inhibition tests using M. fortuitum showed that all evaluated derivatives were able to inhibit biofilm formation even at low concentrations. In terms of structural-activity relationships; the results generated by this study demonstrate that the compounds with bulky substituents on the piperazine subunit were much more active than those with less bulky groups, or no groups. Importantly, the derivatives with a sulfonamide side chain were the most potent compounds. A further observation was that those compounds with a para-substituted benzenesulfonamide ring stand out, regardless of whether this substituent is a donor or an electron-withdrawing group.

Solid state characterization, solubility, intrinsic dissolution and stability behavior of allopurinol hydrochloride salt.

Since each solid form of an active pharmaceutical ingredient (API) can exhibit particular physicochemical properties, the objectives of this work were to characterize and study the solubility/stability properties of allopurinol hydrochloride salt (ALO-HCl) for the first time. ALO-HCl was obtained through an unreported recrystallization process and studied by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All characterization techniques were effective for the differentiation of ALO-HCl from the preferred pharmaceutical form (ALO). DSC and TGA studies showed a solid-state conversion from ALO-HCl to ALO upon HCl loss. Solubility and dissolution tests showed that ALO-HCl converts to ALO in aqueous media. Moreover, the effect of the common ion decreased the amount of drug released from ALO-HCl during the intrinsic dissolution assay in HCl medium. The stability studies showed a partial conversion from ALO-HCl to ALO after 6 months of storage. The results indicate that comparative studies between crystalline forms of APIs are of great importance, as they contribute to the understanding of aspects related to the quality of medicines.

Crosslinked poly (4-vinylpyridine-ethylene glycol dimethacrylate) used for preconcentration of Cd(II) and its determination by flow injection flame atomic absorption spectrometry.

The main purpose of this research was to synthesize crosslinked poly(4-vinylpyridine-ethylene glycol dimethacrylate) and evaluate its feasibility for highly sensitive and selective determination of Cd in water samples by using flow injection flame atomic absorption spectrometry. The crosslinked polymer, prepared by bulk polymerization, was characterized by FTIR spectrometry and scanning electron microscopy. The flow injection solid-phase method was based on preconcentration of 20.0 mL of sample through 100 mg of the polymer packed into a minicolumn at pH 8.25 using a flow rate of 6.0 mL/min, followed by elution with 1.0 M HNO3. The sample solution parameters influencing the preconcentration behavior of Cd ions, such as pH, buffer concentration, and flow rate, were simultaneously studied and optimized using a Doehlert matrix. Values of 0.10 microg/L, 2.0-210 microg/L, 32.3, 18/h, 9.7/min, and 0.62 mL were obtained for LOD, linear range, preconcentration factor, sample throughput, concentration efficiency, and consumption index, respectively. The effect of the presence of the inorganic cations Pb(II), U(IV), Co(II), Hg(II), Cu(II), As(II), Mg(II), Sb(III), Ni(II), Th(IV), Ba(II), and Ca(II) on the method was studied, and the preconcentration of Cd was observed to have no interference. The accuracy of the method was assessed by analysis of natural water samples using addition and recovery tests and inductively coupled plasma/MS as a reference technique, as well as by analysis of a standard reference material of trace elements in water.

Multivariate development and validation of a stability-indicating HPLC method for the determination of glimepiride in tablets.

This paper describes the multivariate development of a stability-indicating HPLC method for the quantification of glimepiride in pharmaceutical tablets. Full factorial design, Doehlert design, and response-surface methodology were used in conjunction with the desirability function approach. This procedure allowed the adequate separation of glimepiride from all degradant peaks in a short analysis time (about 9 min). This HPLC method uses potassium phosphate buffer (pH 6.5; 27.5 mmol/L)-methanol (34 + 66, v/v) mobile phase at a flow rate of 1.0 mL/min and UV detection at 228 nm. A Waters Symmetry C18 column (250 x 4.6 mm, 5.0 pm) at controlled room temperature (25 degrees C) was used as the stationary phase. The method was validated according to International Conference on Harmonization guidelines and demonstrated linearity from 2 to 40 mg/L glimepiride, selectivity, precision, accuracy, and robustness. The LOD and LOQ were 0.315 and 1.050 mg/L, respectively. The multivariate strategy adopted in this work can be successfully applied in routine laboratories because of its fast optimization without the additional cost of columns or equipment.

A New Crystalline Ketoprofen Sodium Salt: Solid-State Characterization, Solubility, and Stability.

Ketoprofen (KTP) is an Active Pharmaceutical Ingredient (API) that has low solubility in aqueous solvents. The use of KTP salts has attracted attention due to its improvements in terms of solubility, tolerability, higher rate and extent of absorption, and faster onset of the therapeutic effect. In this work, a crystalline KTP sodium salt (coded as KTP-Na) was successfully obtained and widely characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), solubility and accelerated stability studies. XRD results showed that KTP-Na is not yet reported in the literature. Moreover, FTIR, DSC and TGA were useful for differentiation of KTP-Na from the KTP commercialized form (coded as KTP-R1). The solubility of KTP-Na in water was about 80 times greater than the KTP-R1. However, KTP-Na showed lower physical stability in storage conditions at 40 ± 2°C/ 75% ± 5% RH when compared to KTP-R1, which was shown to be related to a high hygroscopicity of KTP-Na. Therefore, due to its higher solubility, KTP-Na may be a viable alternative for use in solid dosage forms. However, the presence of moisture must be strictly controlled to avoid water absorption and consequent amorphization.

Mucoadhesive nanostructured lipid carriers as a cannabidiol nasal delivery system for the treatment of neuropathic pain.

The therapeutic potential of cannabidiol (CBD) has been explored to treat several pathologies, including those in which pain is prevalent. However, the oral bioavailability of CBD is low owing to its high lipophilicity and extensive first-pass metabolism. Considering the ability of the nasal route to prevent liver metabolism and increase brain bioavailability, we developed nanostructured lipid carriers (NLCs) for the nasal administration of CBD. We prepared particles with a positively charged surface, employing stearic acid, oleic acid, Span 20Ⓡ, and cetylpyridinium chloride to obtain mucoadhesive formulations. Characterisation of the CBD-NLC dispersions showed uniform nano-sized particles with diameters smaller than 200 nm, and high drug encapsulation. The mucoadhesion of cationic particles has been related to interactions with negatively charged mucin. Next, we added in-situ gelling polymers to the CBD-NLC dispersion to obtain a CBD-NLC-gel. A thermo-reversible in-situ forming gel was prepared by the addition of PluronicsⓇ. CBD-NLC-gel was characterised by its gelation temperature, rheological behaviour, and mucoadhesion. Both formulations, CBD-NLC and CBD-NLC-gel, showed high mucoadhesion, as assessed by the flow-through method and similar in vitro drug release profiles. The in vivo evaluation showed that CBD-NLC dispersion (without gel), administered intranasally, produced a more significant and lasting antinociceptive effect in animals with neuropathic pain than the oral or nasal administration of CBD solution. However, the nasal administration of CBD-NLC-gel did not lessen mechanical allodynia. These findings demonstrate that in-situ gelling hydrogels are not suitable vehicles for highly lipophilic drugs such as CBD, while cationic CBD-NLC dispersions are promising formulations for the nasal administration of CBD.

A review of analytical techniques for determination of glimepiride: present and perspectives.

Glimepiride is an oral antidiabetic drug in the sulfonylurea class, which is widely used in treatment of Type 2 diabetes and it is currently available in more than 60 countries worldwide. As a result of the importance of this oral hypoglycemic agent in the treatment of noninsulin-dependent diabetes mellitus, this work aims to compile the published analytical methods reported so far in the literature for determination of glimepiride in biologic samples and pharmaceutical formulations. Techniques like high-performance liquid chromatography with ultraviolet, array-diode, mass spectroscopy, evaporative light scattering and charged aerosol detections, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry, liquid chromatography-electrospray ionization-tandem mass spectrometry, semimicrobore high-performance liquid chromatography with column-switching, micellar electrokinetic chromatography, high-performance thin layer chromatography, polarography, and spectrophotometry have been used for analysis, from which it can be seen that high-performance liquid chromatography methods have been used most extensively.

A Critical Review of Analytical Methods in Pharmaceutical Matrices for Determination of Corticosteroids.

Corticosteroids are a class of hormones released by the adrenal cortex, which includes glucocorticoids and mineralocorticoids. Glucocorticoids have an important role in the metabolism of carbohydrates, proteins and calcium and effective anti-inflammatory and immunosuppressive activity. Due to their intense immunomodulatory and anti-inflammatory activity, glucocorticoids are used in the treatment of various inflammatory, malignant, allergic conditions such as rhinitis, asthma, dermatological, rheumatic, ophthalmic and neurological diseases, as well as after organ transplants. They are the most widely prescribed drugs in the world. The objective of this review is to provide an overview of the analytical methods in pharmaceutical matrices for determination of corticosteroids. In this study, the predominance of liquid chromatography methods for the analysis of corticosteroids from pharmaceutical products is evident for both liquid and semisolid dosage forms as well as for solids. The same can be said for topical, oral and parenteral formulations. Methods such as spectrophotometry are also used, but given the advantages of chromatographic methods such as better selectivity and sensitivity, they have become the choice for analysis of these drugs, however, most methods still do not meet the credentials of "green chemistry."

Solid-State Characterization of Spironolactone 1/3 Hydrate.

Spironolactone (SPR) is a poorly water-soluble drug widely used for the treatment of various diseases. The objective of this study was to carry out the preparation and solid-state characterization of SPR 1/3 hydrate. The solid form was generated by an unreported recrystallization process in acetone and characterized for the first time by a combination of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), equilibrium solubility, and an accelerated stability study. XRD, DSC, and TGA studies revealed that SPR 1/3 hydrated converts completely to form II after heating to 180°C. Solubility studies at 37°C showed that SPR 1/3 hydrate was statistically less soluble than SPR form II in all tested media and that SPR form II partially converts to SPR 1/3 hydrate in aqueous media. Accelerated stability studies demonstrated that both forms were physically and chemically stable up to 6 months (40°C/75% RH). We concluded that contamination of SPR 1/3 hydrate in SPR raw materials is undesirable. Taking this into account we recommend its polymorphic monitoring either in active pharmaceutical ingredients or commercial tablets by solid-state identification/quantification methods (XRD, DSC, TGA, and FTIR). Of these, XRD proved to be the most conclusive and accurate.

Analysis of polymorphic contamination in meloxicam raw materials and its effects on the physicochemical quality of drug product.

This work aims to evaluate the effect of polymorphism on the physicochemical properties of meloxicam, which is an antipyretic and non-steroidal anti-inflammatory drug. Powder X-ray Diffraction, Infrared Spectroscopy with attenuated total reflectance, Thermogravimetric and Differential Scanning Calorimetry techniques were used for the polymorphic characterization. Comparative tests of solubility, intrinsic dissolution and dissolution profiles were performed on meloxicam active pharmaceutical ingredients (APIs) and formulated tablets. A polymorphic contamination (Forms I and III) was found in a studied meloxicam batch, which showed a higher solubility and greater intrinsic dissolution than those containing only the preconized form (Form I). Consequently, the dissolution profiles of the tablets that contained the polymorphic contamination showed higher drug release. Additionally, a thermal behavior study shows that MLX Form I and III are monotropy polymorphs being MLX Form III a metastable phase, which becomes MLX Form I at approximately 200°C in solid state phase transition governed by kinetic variables. The kinetic of conversion of Form III to Form I in saturated solutions was also studied. These results illustrate the importance of the polymorphic characterization of meloxicam APIs and formulated tablets in order to avoid potential quality and efficacy problems of drug products.

Quantification of bufadienolides in the poisons of Rhinella marina and Rhaebo guttatus by HPLC-UV.

Bufadienolides are the main active compounds in the Bufonidae family of frogs. Recent studies have demonstrated cytotoxic and/or antitumor activity in these molecules. A HPLC-DAD method was developed and validated to quantify three bufadienolides (telocinobufagin, marinobufagin and bufalin) in ethyl acetate extracts of the cane toad poison frogs and smooth-sided toad. The chromatographic analysis was performed on Phenomenex Luna C18 (250.0 × 4.6 mm, 5 µm), using gradient elution with acetonitrile and water, at a flow rate of 1.0 mL min(-1) and detection at 296 nm. The method showed linearity (r > 0.999) and adequate recovery values (86%-111%). The limits of quantification of bufadienolides were 7.4 µg mL(-1) for telocinobufagin, 4.2 µg mL(-1) for marinobufagin and 4.0 µg mL(-1) for bufalin. Intraday and interday values of the method were evaluated and presented standard deviation values lower than 5%. The method was successfully applied to quantify the bufadienolides in the venom extract of the cane toad, which showed a content of 60% of marinobufagin. The same method was not selective for the venom extract of the Rhaebo guttatus, despite being linear, accurate and precise, requiring the development of a technique that presents a greater selectivity.

Identification and proportion of the enantiomers of the antihypertensive drug chlortalidone in its Form II by high quality single-crystal X-ray diffraction data.

Chlortalidone (CTD) is a diuretic drug largely used as part of antihypertensive therapies. It is marketed as an equimolar mixture of its enantiomers in the racemic crystal phase named Form I, despite of the higher aqueous solubility of another crystal form. The latter, named Form II, was thought to contain both enantiomers as a racemic conglomerate, i.e., in the form of a mixture of crystals, half of which consists solely of the (R)-enantiomer, the other half the (S)-enantiomer. The occurrence of both enantiomers in individual crystals of CTD Form II was demonstrated in this study. Spontaneous resolution does really occur upon crystallization, as presumed previously even without physical evidence of the (S)-enantiomer. Both (R) and (S)-enantiomers were successfully identified as two domains of a twinned by inversion single crystal of CTD Form II. A reliable Flack parameter of 0.14(4) allowed to determine the proportion of the enantiomers in the crystal, which is formed with 86% of the (R)-enantiomer and 14% of the (S)-enantiomer.

Analysis of chlorthalidone polymorphs in raw materials and tablets and the effect of forms I and II on the dissolution properties of drug products.

Chlorthalidone (CTD) is an antihypertensive drug and exhibits four crystalline forms: I, II, III and IV. In this paper, the incidence of CTD polymorphs in raw materials and in tablets as well as the solubility and dissolution properties of forms I and II have been studied. Raw materials were named as A, B, C, D, and E and tablets as Reference, G1, G2 and S. Using powder X-ray diffraction and infrared spectroscopy analyses we found that A, B, E, Reference and G1 contain CTD form I; C, D and S contain predominantly form II; and G2 contain a mixture of both forms. Solubility experiments showed that form II is up to 49% more soluble than form I and dissolution studies showed a significantly effect of the polymorphism on the dissolution of CTD from tablets. Based on these results, it was concluded that only the CTD form I is acceptable for preparation of tablet form. Moreover, we proposed the polymorphic quality control of CTD raw materials and tablets.

Lamivudine salts with improved solubilities.

To optimize solubility of drugs, current strategies mainly focus on engineering and screening of smart crystal phases. Two salts of the anti-human immunodeficiency virus (HIV) drug lamivudine--namely, lamivudine hydrochloride and lamivudine hydrochloride monohydrate, were prepared in the course of screening the crystallization conditions of lamivudine duplex, an uncommon DNA-mimic, double-stranded helical structure made up of partially protonated drug pairs. Here, water solubilities of lamivudine hydrochloride, lamivudine hydrochloride monohydrate, and lamivudine duplex are reported. The aqueous solubility of this anti-HIV drug was significantly increased in both salts and also in lamivudine duplex in relation to the water solubility of lamivudine form II. In comparison with the lamivudine form II incorporated into therapeutic formulations, the drug solubility was increased at a temperature of 299 ± 2 K by factors of 1.2, 3.3, and 4.5 in lamivudine hydrochloride, lamivudine hydrochloride monohydrate, and lamivudine duplex, respectively, demonstrating that this solid-state property of lamivudine can be improved by crystal engineering strategies. Solubility profiles were understood on the basis of structural and solvent-solute interaction approaches. At last, correlations between solubility and crystal structures allowed for a rational approach to understand how this physicochemical feature could be enhanced by engineering new salts of the drug.

Determination and validation of secnidazole in tablets by UV spectrophotometric / Determinação e validação do secnidazol em comprimidos por espectrofotometria na região do ultravioleta

Secnidazole, a 5-nitroimidazole, is a drug used in the treatment against protozoa, and several bacterial infections. This study purpose was to develop and validate a UV spectrophotometric method to determine secnidazole in pharmaceutical tablet dosage forms once there is no method reported in the pharmacopoeia yet. The quantification was performed using methanol as solvent at 325 nm (maximum wavelength) and three kinds of products marketed in Brazil (reference, generic and similar tablets) containing 1g of secnidazole. The method obeyed Beer's law in the concentration range of 4 - 20 µgmL-1 respectively. The method was validated according to the International Conference on Harmonization (ICH) and Brazil National Health Surveillance Agency (ANVISA) guidelines, showing accuracy, precision, selectivity, robustness and linearity. Tests such as weight range, friability, disintegration, hardness and dissolution were carried out to check tablets' quality and all the trials showed to be in accordance with the general test guidelines of the Brazilian Pharmacopoeia. The dissolution test was carried out and the developed method was applied. The method developed is suitable for the estimation of secnidazole in tablets without any interference from the excipients and can be used for routine in quality control. Still, it's a simple, fast and low cost method.

Secnidazol, um nitroimidazólico, é um fármaco utilizado no tratamento para protozoários, e várias infecções bacterianas. Este trabalho propôs o desenvolvimento e validação de um método espectrofotométrico na região do ultravioleta para a determinação de Secnidazol na forma farmacêutica de comprimidos, uma vez que não há nenhum método relatado nas farmacopeias. A quantificação foi realizada utilizando metanol como solvente a 325 nm (máximo de comprimento de onda) e usando três tipos de produtos comercializados no Brasil (de referência, genéricos e comprimidos similares) contendo 1g de Secnidazol. O método obedeceu a lei de Beer no intervalo de concentração de 4 - 20 µgmL-1, respectivamente. O método foi validado de acordo com a Conferência Internacional de Harmonização (ICH) e diretrizes da Agência Nacional de Vigilância Sanitária do Brasil (ANVISA), apresentando exatidão, precisão, seletividade, robustez e linearidade. Testes como variação de peso, friabilidade, desintegração, dureza e dissolução foram realizados para verificar a qualidade de comprimidos e mostrou-se de acordo com os testes gerais da Farmacopeia Brasileira. O teste de dissolução realizado e o método desenvolvido pode ser aplicado. O método desenvolvido é adequado para a estimativa de secnidazole em comprimidos sem qualquer interferência dos excipientes e pode ser usado para a rotina de controlo de qualidade. Ainda, é um método simples, rápido e de baixo custo.

Avaliação da qualidade de medicamentos contendo clortalidona / Quality Assessment of medication containing chlorthalidone

Os diuréticos são a classe de fármacos mais utilizados no tratamento da hipertensão devido a sua eficácia terapêutica e ao baixo custo. Isto faz com que uma grande variedade de medicamentos esteja disponível no comercio e atrelado a este fator muitas empresas tem seus lotes de medicamentos suspensos devido a desvios de qualidade e das modificações realizadas nas formulações após o seu registro. A clortalidona é um diurético tiazídico indicada para o tratamento de hipertensão arterial leve ou moderada e com normalidade das funções cardíacas e renal. Este trabalho teve como objetivo verificar a qualidade de comprimidos de clortalidona comercializados no município de Sinop/ MT. O controle de qualidade foi realizado como estabelecido na Farmacopeia Brasileira quinta edição (ensaios de identificação, pureza, doseamento, ensaios referentes a forma farmacêutica de comprimidos e perfil de dissolução), de cinco produtos contendo clortalidona 25 mg sendo um produto de medicamento referência, dois de medicamentos genéricos e dois de medicamentos similares. Verificou-se que todos os produtos foram aprovados, cumprindo com todos os requisitos exigidos nos ensaios de qualidade e que estudos referentes ao perfil de dissolução nos lotes de produção de medicamentos são importantes para prever a absorção adequada do princípio ativo

Diuretics are the most used class of drugs that are used to treat hypertension because of their therapeutic efficiency and low cost. This makes a wide variety of medicines commercially available and, linked to this factor, many companies have their batches of medicines suspended due to deviations of quality and modifications made in the formulas after their registration. Chlorthalidone, is a thiazide diuretic drug indicated for treatment of hypertension of patients with mild or moderate hypertension, and with normal cardiac and renal function. This work aimed to assess and compare the quality of medicines containing chlorthalidone commercialized in Sinop-MT. The quality control was performed as established in the fifth edition of the Brazilian Pharmacopoeia (identification, purity and dosage assays, tests referring to the pharmaceutical form of the tablets and their dissolution profile). Among five products containing 25 mg of chlortalidone, one was a reference drug product, two were generic and two were similar drugs. It was found that all products were approved, meeting all the requirements required in the quality tests, and that studies concerning the dissolution profile in batches of drug production are important to predict adequate absorption of the active principle

Solubility and dissolution studies of tibolone polymorphs

ABSTRACT Different solid forms of an active pharmaceutical ingredient can have distinct chemical and physical characteristics. In this work, we studied the solubility and dissolution properties of the described tibolone polymorphic forms (I and II). Both forms were successively recrystallized and characterized by powder X-ray diffraction and attenuated total reflection infrared spectroscopy. Equilibrium solubility and dissolution profiles were performed for both forms. Solubility studies demonstrated that form II is statistically more soluble in water, 0.01 mol L-1 HCl and pH 4.5 acetate buffer. The solubility of forms I and II were explained in terms of crystal packing. Dissolution tests of tablets showed a lower release of polymorphic form II than form I from tablets. The results showed an impact of polymorphism on the quality of tibolone tablets and suggest that tibolone forms I and II can show distinct interactions with pharmaceutical excipients used in tablets. Therefore, only form I is acceptable for the preparation of tablet forms. Based on our results, we propose the quality control on tibolone raw materials using X-ray diffraction analysis and attenuated total reflection infrared spectroscopy.

A discriminating dissolution method for glimepiride polymorphs.

Glimepiride, an oral antidiabetic drug, is practically insoluble in water and exists in two polymorphic forms, I and II, of which form II has higher solubility in water. Because the dissolution rate of drugs can depend on the crystal form, there is a need to develop discriminating dissolution methods that are sensitive to changes in polymorphic forms. In this work, a dissolution method for the assessment of 4 mg glimepiride tablets was developed and validated. The optimal dissolution conditions were 1000 mL of phosphate buffer (pH 6.8) containing 0.1% (w/v) of sodium dodecyl sulfate as the dissolution medium and a stirring speed of 50 rpm using a paddle apparatus. The results demonstrated that all the data meet the validation acceptance criteria. Subsequently, tablets containing forms I and II of glimepiride were prepared and subjected to dissolution testing. A significant influence of polymorphism on the dissolution properties of glimepiride tablets was observed. These results suggested that the raw material used to produce glimepiride tablets must be strictly controlled because they may produce undesirable and unpredictable effects.

Analysis of spironolactone polymorphs in active pharmaceutical ingredients and their effect on tablet dissolution profiles

ABSTRACT Spironolactone (SPR) is a steroidal drug administered as a potassium-sparing diuretic for high blood pressure treatment. The drug shows incomplete gastrointestinal absorption due to its poor aqueous solubility. The physicochemical properties of SPR in crystal forms I and II suggest that differences in their aqueous solubility may lead to a lack of bioequivalence between solid-state formulations. In this study, SPR polymorphs in five batches of active pharmaceutical ingredients (APIs) from three manufacturers were characterized using powder X-ray diffraction, infrared spectroscopy, thermal analysis, and solubility measurements. SPR tablets (50 mg) were manufactured in our laboratory using API in pure form II, and API in form II contaminated with form I, which was found in a commercial batch. Physicochemical quality evaluations of the manufactured tablets, along with five SPR tablets marketed in Brazil, were performed, and results indicated differences in their dissolution profiles. In the manufactured tablets, differences were associated with the increased solubility of API in form II contaminated with form I compared to API in pure form II. In the marketed SPR tablets, the formulation composition demonstrated an important role in the dissolution rate of the drug, leading to lack of pharmaceutical equivalence among the drug products.

Multivariate optimization and validation of an analytical methodology by RP-HPLC for the determination of losartan potassium in capsules.

This paper describes the optimization and validation of an analytical methodology for the determination of losartan potassium in capsules by HPLC using 2(5-1) fractional factorial and Doehlert designs. This multivariate approach allows a considerable improvement in chromatographic performance using fewer experiments, without additional cost for columns or other equipment. The HPLC method utilized potassium phosphate buffer (pH 6.2; 58 mmol L(-1))-acetonitrile (65:35, v/v) as the mobile phase, pumped at a flow rate of 1.0 mL min(-1). An octylsilane column (100 mm x 4.6mm i.d., 5 microm) maintained at 35 degrees C was used as the stationary phase. UV detection was performed at 254 nm. The method was validated according to the ICH guidelines, showing accuracy, precision (intra-day relative standard deviation (R.S.D.) and inter-day R.S.D values <2.0%), selectivity, robustness and linearity (r=0.9998) over a concentration range from 30 to 70 mg L(-1) of losartan potassium. The limits of detection and quantification were 0.114 and 0.420 mg L(-1), respectively. The validated method may be used to quantify losartan potassium in capsules and to determine the stability of this drug.