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1.
Mol Pharm ; 14(10): 3370-3380, 2017 10 02.
Article in English | MEDLINE | ID: mdl-28787567

ABSTRACT

In this paper, a novel approach to determine stable concentration in API-polymer systems is presented. As a model, binary amorphous mixtures flutamide (FL) drug with a copolymer Kollidon VA64 (PVP/VA) have been used. It is worthwhile to note that finding an effective method to achieve this goal is a matter of great importance because physical stability of the amorphous pharmaceuticals is the key issue that is investigated worldwide. Due to the fact that molecular dynamics was found to be the crucial factor affecting physical stability of disordered pharmaceuticals, we examined it for both neat FL and its PVP/VA mixtures by means of broadband dielectric spectroscopy (BDS). Thorough investigation of the impact of polymeric additive on the molecular mobility of disordered FL reveals unusual, previously unreported behavior. Namely, simultaneously with the beginning of the recrystallization process, we observe some transformation from unstable supersaturated concentration of investigated mixture to the different, unknown concentration of FL-PVP/VA. Observed, during BDS experiment, transformation enables us to determine the limiting, highly physically stable concentration of FL in PVP/VA polymer (saturated solution), which is equivalent to FL + 41% wt. of PVP/VA. The described high physical stability of this unveiled system has been confirmed by means of long-term XRD measurements. According to our knowledge, this is the first time when such a behavior has been observed by means of BDS.


Subject(s)
Dielectric Spectroscopy/methods , Drug Stability , Calorimetry, Differential Scanning , Chemistry, Pharmaceutical/methods , Crystallization , Flutamide/chemistry , Models, Chemical , Pyrrolidines/chemistry , Solubility , Thermodynamics , Vinyl Compounds/chemistry
2.
Eur J Pharm Biopharm ; 109: 14-23, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27658987

ABSTRACT

The aim of this research was to develop immediate release tablets comprising solid dispersion (IRSDTs) of tadalafil (Td) in a vinylpyrrolidone and vinyl acetate block copolymer (PVP-VA), characterized by improved dissolution profiles. The solid dispersion of Td in PVP-VA (Td/PVP-VA) in a weight ratio of 1:1 (w/w) was prepared using two different processes i.e. spray drying and ball milling. While the former process has been well established in the formulation of IRSDTs the latter has not been exploited in these systems yet. Regardless of the preparation method, both Td/PVP-VA solid dispersions were amorphous as confirmed by PXRD, DSC and FTIR. However, different morphology of particles (SEM) resulted in differences in water apparent solubility and disk intrinsic dissolution rate (DIDR). Both solid dispersions and crystalline Td were successfully made into directly compressible tablets at three doses of Td, i.e. 2.5mg, 10mgand20mg, yielding nine different formulations (D1-D9). Each of the lots met the requirements set by Ph.Eur. and was evaluated with respect to appearance, diameter, thickness, mass, hardness, friability, disintegration time and content of Td. IRSDTs performed as supersaturable formulations and had significantly improved water dissolution profiles in comparison with equivalent tablets containing crystalline Td and the marketed formulations. Tablets with both spray dried and ball milled Td/PVP-VA revealed the greatest improvement in dissolution depending on the investigated doses, i.e. 2.5mgand20mg, respectively. Also, dissolution of Td from Td/PVP-VA delivered in different forms occurred in the following order: powders>tablets>capsules.


Subject(s)
Drug Compounding/methods , Pyrrolidines/chemistry , Tablets/chemistry , Tadalafil/chemistry , Vinyl Compounds/chemistry , Calorimetry, Differential Scanning , Compressive Strength , Crystallization , Desiccation , Drug Stability , Microscopy, Electron, Scanning , Powders , Solubility , Spectrophotometry, Infrared , Spectroscopy, Fourier Transform Infrared , X-Ray Diffraction
3.
Mol Pharm ; 12(10): 3628-38, 2015 Oct 05.
Article in English | MEDLINE | ID: mdl-26323061

ABSTRACT

The aim of this article is to examine the crystallization tendencies of three chemically related amorphous anti-inflammatory agents, etoricoxib, celecoxib, and rofecoxib. Since the molecular mobility is considered as one of the factors affecting the crystallization behavior of a given material, broadband dielectric spectroscopy was used to gain insight into the molecular dynamics of the selected active pharmaceutical ingredients. Interestingly, our experiments did not reveal any significant differences in their relaxation behavior either in the supercooled liquid or in the glassy state. Hence, as a possible explanation for the enhanced physical stability of etoricoxib, its ability to undergo a tautomerization reaction was recognized. The occurrence of intramolecular proton transfer in the disordered etoricoxib was proven experimentally by time-dependent dielectric and infrared (IR) measurements. Additionally, IR spectroscopy combined with density functional theory calculations pointed out that in the etoricoxib drug, being in fact a binary mixture of tautomers, the individual isomers may interact with each other through a hydrogen bonding network. A possible explanation of this issue was achieved by performing dielectric experiments at elevated pressure. Since compression results in etoricoxib recrystallization, the possible influence of pressure on the observed stabilization effect is also carefully discussed.


Subject(s)
Anti-Inflammatory Agents/chemistry , Celecoxib/chemistry , Drug Stability , Lactones/chemistry , Pyridines/chemistry , Sulfones/chemistry , Crystallization , Dielectric Spectroscopy , Etoricoxib
4.
Eur J Pharm Biopharm ; 96: 237-46, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26247119

ABSTRACT

The aim of this paper was to evaluate physical stability of solid dispersions in respect to the drug, tadalafil (Td), in vinylpyrrolidone and vinyl acetate block copolymer (PVP-VA). Nine solid dispersions of Td in PVP-VA (Td/PVP-VA) varied in terms of quantitative composition (1:9-9:1, w/w) were successfully produced by spray-drying. Their amorphous nature, supersaturated character and molecular level of mixing (a solid solution structure) were subsequently confirmed using DSC, PXRD, SEM and calculation of Hansen total solubility parameters. Due to thermal degradation of both components before the melting point of Td (302.3°C), an approach based on the drug crystallization from the supersaturated solid dispersion was selected to calculate the solubility of Td in the polymer. Annealing of the Td/PVP-VA solid dispersion (1:1, w/w) at selected temperatures above its Tg resulted in different stable solid dispersions. According to the Gordon-Taylor equation their new Tgs gave the information about the quantitative composition which corresponded to the thermodynamic solubility of Td in PVP-VA at given temperatures of annealing. The obtained relationship was fitted to the exponential function, with the calculated solubility of Td of 20.5% at 25°C. This value was in accordance with the results of hot stage polarizing light microscopy as well as stability tests carried out at 80°C and 0% RH, in which Td solid dispersions containing 10-20% of the drug were the only systems that did not crystallize within two months. A thermal analysis protocol utilizing a fast heating rate was shown to generate Td solubility data complementing the solid dispersion method. The Flory-Huggins model applied for the Td/PVP-VA system yielded the solubility value of 0.1% at 25°C, showing the lack of applicability in this case.


Subject(s)
Excipients/chemistry , Phosphodiesterase 5 Inhibitors/chemistry , Pyrrolidines/chemistry , Tadalafil/chemistry , Vasodilator Agents/chemistry , Vinyl Compounds/chemistry , Chemical Phenomena , Drug Carriers/administration & dosage , Drug Carriers/chemistry , Drug Compounding , Drug Stability , Drug Storage , Hot Temperature/adverse effects , Phosphodiesterase 5 Inhibitors/administration & dosage , Solubility , Suspensions , Tadalafil/administration & dosage , Thermodynamics , Transition Temperature , Vasodilator Agents/administration & dosage
5.
Eur J Pharm Biopharm ; 94: 106-15, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25998701

ABSTRACT

To improve solubility of tadalafil (Td), a poorly soluble drug substance (3µg/ml) belonging to the II class of the Biopharmaceutical Classification System, its six different solid dispersions (1:1, w/w) in the following polymers: HPMC, MC, PVP, PVP-VA, Kollicoat IR and Soluplus were successfully produced by freeze-drying. Scanning electron microscopy showed a morphological structure of solid dispersions typical of lyophilisates. Apparent solubility and intrinsic dissolution rate studies revealed the greatest, a 16-fold, increase in drug solubility (50µg/ml) and a significant, 20-fold, dissolution rate enhancement for the Td/PVP-VA solid dispersion in comparison with crystalline Td. However, the longest duration of the supersaturation state in water (27µg/ml) over 24h was observed for the Td solid dispersion in HPMC. The improved dissolution of Td from Td/PVP-VA was confirmed in the standard dissolution test of capsules filled with solid dispersions. Powder X-ray diffraction and thermal analysis showed the amorphous nature of these binary systems and indicated the existence of dispersion at the molecular level and its supersaturated character, respectively. Nevertheless, as evidenced by film casting, the greatest ability to dissolve Td in polymer was determined for PVP-VA. The crystallization tendency of Td dispersed in Kollicoat IR could be explained by the low Tg (113°C) of the solid dispersion and the highest difference in Hansen solubility parameters (6.8MPa(0.5)) between Td and the polymer, although this relationship was not satisfied for the partially crystalline dispersion in PVP. Similarly, no correlation was found between the strength of hydrogen bonds investigated using infrared spectroscopy and the physical stability of solid dispersions or the level of supersaturation in aqueous solution.


Subject(s)
Hypromellose Derivatives/chemistry , Pyrrolidines/chemistry , Tadalafil/chemistry , Vinyl Compounds/chemistry , Calorimetry, Differential Scanning , Capsules , Chemistry, Pharmaceutical , Crystallography, X-Ray , Drug Stability , Freeze Drying , Hydrogen Bonding , Kinetics , Microscopy, Electron, Scanning , Powder Diffraction , Powders , Solubility , Spectroscopy, Fourier Transform Infrared , Technology, Pharmaceutical/methods , Temperature
6.
Mol Pharm ; 11(11): 4280-90, 2014 Nov 03.
Article in English | MEDLINE | ID: mdl-25310722

ABSTRACT

The purpose of this paper is to examine the role of molecular mobility in the recrystallization process from the amorphous state of the anticholesterol drug ezetimibe. Both the molecular dynamics and crystallization kinetics have been studied using various experimental techniques, such as broadband dielectric spectroscopy (BDS), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Our investigations have shown that ezetimibe easily recrystallizes from the disordered state, both below and above its glass transition temperature (Tg = 336 K). Moreover, we found that an only slightly elevated pressure (5 MPa) significantly accelerates the recrystallization process at T > Tg. We predict that the structural relaxation time of amorphous ezetimibe at 293 K (storage temperature) and ambient pressure is only 22 days. This result corresponds to the characteristic time, determined from XRD measurements, for amorphous ezetimibe to recrystallize during storage at Troom = 298 K. It leads to the conclusion that the molecular mobility reflected in structural relaxation of ezetimibe is mainly responsible for devitrification of this drug. Finally, we determined a relatively easy way to improve the physical stability of the drug by preparing a binary amorphous ezetimibe-Soluplus mixture. Ezetimibe in an amorphous mixture with 20 wt % Soluplus has a much better (over six times) solubility than the pure crystalline material.


Subject(s)
Anticholesteremic Agents/chemistry , Azetidines/chemistry , Drug Stability , Molecular Dynamics Simulation , Calorimetry, Differential Scanning , Crystallization , Dielectric Spectroscopy , Ezetimibe , Kinetics , Transition Temperature , X-Ray Diffraction
7.
Eur J Pharm Sci ; 62: 132-40, 2014 Oct 01.
Article in English | MEDLINE | ID: mdl-24907679

ABSTRACT

This study for the first time investigates the solubility and dissolution rate of amorphous tadalafil (Td)--a poorly water soluble chemical compound which is commonly used for treating the erectile dysfunction. To convert the crystalline form of Td drug to its amorphous counterpart we have employed most of the commercially available amorphization techniques i.e. vitrification, cryogenic grinding, ball milling, spray drying, freeze drying and antisolvent precipitation. Among the mentioned methods only quenched cooling of the molten sample was found to be an inappropriate method of Td amorphization. This is due to the thermal decomposition of Td above 200°C, as proved by the thermogravimetric analysis (TGA). Disordered character of all examined samples was confirmed using differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD). In the case of most amorphous powders, the largest 3-fold increase of apparent solubility was observed after 5 min, indicating their fast recrystallization in water. On the other hand, the partially amorphous precipitate of Td and hypromellose enhanced the solubility of Td approximately 14 times, as compared with a crystalline substance, which remained constant for half an hour. Finally, disk intrinsic dissolution rate (DIDR) of amorphous forms of Td was also examined.


Subject(s)
Carbolines/chemistry , Phosphodiesterase 5 Inhibitors/chemistry , Calorimetry, Differential Scanning , Drug Compounding/methods , Drug Liberation , Powder Diffraction , Solubility , Spectroscopy, Fourier Transform Infrared , Tadalafil , Thermogravimetry , X-Ray Diffraction
8.
Iran J Pharm Res ; 13(1): 29-37, 2014.
Article in English | MEDLINE | ID: mdl-24734054

ABSTRACT

The objective of the study was to compare pharmacokinetic and pharmacodynamic parameters of gliclazide after administration of immediate (IR) and modified release (MR) tablets. The experiment included rats with both normoglycemia and streptozocin (STZ)-induced hyperglycemia. Several MR formulations were designed and in-vitro drug release profile was assessed by a dissolution test. For the further in-vivo study the most suitable formulation was chosen. For pharmacokinetic analysis concentrations of gliclazide in plasma were determined by a validated high performance liquid chromatography (HPLC) method with UV detection. Pharmacodynamic efficacy of the drug was evaluated by measuring blood glucose concentrations. Gliclazide bioavailability was totally different for two formulations in both healthy and diabetic rats based on area under the curve (AUC), time to peak concentration (tmax) and peak concentration (Cmax). Reduction of blood glucose level was significantly higher after the administration of IR than MR formulation. The highest pharmacodynamic efficacy of gliclazide was observed in the normal animals group after administration of the IR tablets, while hypoglycemic effect of the drug was diminished in animals with induced diabetes. Our study suggested that results of reduction in blood glucose level for STZ-induced groups were not comparable with pharmacodynamic effect for normal group. It may be assumed that a decrease in glycemia in healthy subjects might not be a suitable factor for characterizing anti-diabetic drugs.

9.
Mol Pharm ; 10(10): 3612-27, 2013 Oct 07.
Article in English | MEDLINE | ID: mdl-24070615

ABSTRACT

This study for the first time investigates physicochemical properties of amorphous indapamide drug (IND), which is a known diuretic agent commonly used in the treatment of hypertension. The solid-state properties of the vitrified, cryomilled and ball-milled IND samples were analyzed using X-ray powder diffraction (XRD), mass spectrometry, nuclear magnetic resonance (NMR), infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). These analytical techniques enabled us (i) to confirm the purity of obtained amorphous samples, (ii) to describe the molecular mobility of IND in the liquid and glassy state, (iii) to determine the parameters describing the liquid-glass transition i.e. Tg and dynamic fragility, (iv) to test the chemical stability of amorphous IND in various temperature conditions and finally (v) to confirm the long-term physical stability of the amorphous samples. These studies were supplemented by density functional theory (DFT) calculations and apparent solubility studies of the amorphous IND in 0.1 M HCl, phosphate buffer (pH=6.8), and water (25 and 37 °C).


Subject(s)
Indapamide/chemistry , Calorimetry, Differential Scanning , Diuretics/chemistry , Drug Stability , Molecular Dynamics Simulation , Solubility , Spectroscopy, Fourier Transform Infrared
10.
Eur J Pharm Biopharm ; 83(1): 114-21, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23085331

ABSTRACT

Telmisartan (TLM), a poorly water-soluble angiotensin II receptor antagonist in crystalline form, was transformed into the amorphous state by the melt quench technique, as well as a cryogenic grinding method, in order to improve its physiochemical properties. The chemical stability of TLM, that is, the tendency of the material to resist change or decomposition due to internal reaction, or due to the effects of air, heat, light, pressure, etc., during formation of the amorphous phase was assessed by monitoring high performance liquid chromatography. The existence of the amorphous state was confirmed by differential scanning calorimetry and X-ray powder diffraction. The glass transition occurred at T(g)=401K. In the next stage, the solubility of TLM in 0.1M HCl, phosphate buffer, pH=6.8, and water (25°C and 37°C) was determined. Both amorphous forms of TLM (vitrified and cryogrinded) had a higher solubility (µg/ml) than their crystalline counterpart. An important and interesting problem of the study was to evaluate how the tableting process was affected by the choice of either a crystalline or an amorphous form of TLM. Eight different tablet formulations were evaluated using both the crystalline and the amorphous form of TLM. Measurements of the physical properties and dissolution tests of G4 formulations tablets with telmisartan in crystalline and amorphous form after different storage periods were also performed.


Subject(s)
Angiotensin II Type 1 Receptor Blockers/chemistry , Benzimidazoles/chemistry , Benzoates/chemistry , Angiotensin II Type 1 Receptor Blockers/administration & dosage , Benzimidazoles/administration & dosage , Benzoates/administration & dosage , Calorimetry, Differential Scanning , Chromatography, High Pressure Liquid , Crystallization , Drug Stability , Drug Storage , Solubility , Tablets , Telmisartan , Temperature , Time Factors , X-Ray Diffraction
11.
Mol Pharm ; 9(5): 1250-61, 2012 May 07.
Article in English | MEDLINE | ID: mdl-22424553

ABSTRACT

In this paper the molecular dynamics of a common local-anesthetic drug, lidocaine hydrochloride (LD-HCl), and its water mixtures were investigated. By means of broadband dielectric spectroscopy and calorimetric measurements it was shown that even a small addition of water causes a significant effect on the relaxation dynamics of analyzed protic ionic liquid. Apart from the two well-resolved relaxations (σ- and γ-processes) and the ß-mode, identified as the JG-process, observed for anhydrous LD-HCl, a new relaxation peak (υ) is visible in the dielectric spectra of aqueous mixtures of this drug. Additionally, the significant effect of the water on the glass transition temperature of LD-HCl was found. The sample characterized with mole fraction of water X(w) = 0.44 reveals the glass transition temperature T(g), 42 K lower than that of anhydrous material (307 K). Finally, it was shown that by amorphization of the hydrochloride salt of lidocaine it is possible to obtain its room temperature ionic liquid form.


Subject(s)
Ionic Liquids/chemistry , Lidocaine/chemistry , Molecular Dynamics Simulation , Calorimetry, Differential Scanning , Magnetic Resonance Spectroscopy , Transition Temperature , X-Ray Diffraction
12.
J Chem Phys ; 134(4): 044517, 2011 Jan 28.
Article in English | MEDLINE | ID: mdl-21280758

ABSTRACT

Broadband dielectric spectroscopy was employed to investigate the relaxation dynamics of supercooled and glassy nonivamide-the synthetic form of capsaicin being the most spicy-hot substance known to man. The material is of great importance in the pharmaceutical industry because it has wide usage in the medical field for relief of pain, and more recently it has been shown to be effective in fighting cancers. Dielectric measurements carried out at various isobaric and isothermal conditions (pressure up to 400 MPa) revealed very narrow α-loss peak and unresolved secondary relaxations appearing in the form of an excess wing on the high frequency flank. Moreover, our studies have shown the shape of dielectric loss spectrum at any fixed loss peak frequency is invariant to different combinations of temperature and pressure, i.e., validity of the time-temperature-pressure superpositioning. We also found the fragility index is nearly constant on varying pressure. This property is likely due to the unusual structure of nonivamide, which has a part characteristic of van der Waals glass-former and another part characteristic of hydrogen-bonded glass-former.


Subject(s)
Benzylamines/chemistry , Fatty Acids/chemistry , Molecular Dynamics Simulation , Benzylamines/pharmacology , Capsaicin/chemistry , Capsaicin/pharmacology , Dielectric Spectroscopy , Fatty Acids/pharmacology , Glass/chemistry , Humans , Hydrogen Bonding , Pressure , Sensory System Agents/chemistry , Sensory System Agents/pharmacology , Temperature , X-Ray Diffraction
13.
Mol Pharm ; 7(5): 1692-707, 2010 Oct 04.
Article in English | MEDLINE | ID: mdl-20669906

ABSTRACT

Glibenclamide (GCM) is an oral hypoglycemic agent of the sulfonylurea group used in the treatment of non-insulin-dependent diabetes. Crystalline GCM is characterized by low bioavailability, which is attributed to its poor dissolution properties. It prompted us to prepare this drug in its amorphous form as a means to enhance its dissolution characteristics. Two different methods were used to convert crystalline GCM into the glassy form: quench-cooling of the melt and cryogenic milling. To monitor solid-state properties of the amorphous samples, X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), ultraperformance liquid chromatography (UPLC) and spectroscopy, and broadband dielectric spectroscopy (BDS) were applied. The results of UPLC separations along with associated infrared and NMR measurements unambiguously showed that the thermal degradation of the quenched GCM, as suggested in literature reports, does not occur. A similar analysis performed on the cryomilled material also did not indicate any chemical decomposition. On the other hand, both methods confirmed that the conversion to the amorphous form is connected with the amide-imidic acid tautomerism of the examined drug. Moreover it was shown that this transformation occurs regardless of the manner of amorphization. Finally, dielectric spectroscopy was employed to study the molecular dynamics of vitrified GCM. The analysis of the ε''(f) in terms of the KWW function from the dielectric measurements revealed the existence of an "excess wing" attributed to the true Johari-Goldstein process based on Ngai's coupling model. The dielectric properties of GCM obtained in the amorphous form both by rapid cooling of the melt and the cryogenic grinding of crystalline sample were also compared.


Subject(s)
Glyburide/chemistry , Administration, Oral , Calorimetry, Differential Scanning , Chemistry, Pharmaceutical , Crystallization , Dielectric Spectroscopy , Drug Stability , Glyburide/administration & dosage , Humans , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/chemistry , Molecular Dynamics Simulation , Powder Diffraction , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis
14.
J Phys Chem B ; 114(19): 6579-93, 2010 May 20.
Article in English | MEDLINE | ID: mdl-20415466

ABSTRACT

Dielectric spectroscopy (DS) was used to investigate the relaxation dynamics of supercooled and glassy ibuprofen at various isobaric and isothermal conditions (pressure up to 1750 MPa). The ambient pressure data are in good agreement with that reported previously in the literature. Our high pressure measurements revealed validity of temperature-pressure superpositioning (TPS) for the alpha-peak. We also found that the value of the fragility index decreases with compression from m = 87 +/- 2 at atmospheric pressure to m = 72.5 +/- 3.5 at high pressure (p = 920 MPa). The drop of fragility observed in our experiment was discussed in the framework of the two-order-parameter (TOP) model. In addition, we have also studied crystallization kinetics in a liquid state of examined drug at ambient and high pressure. We found out that, for the same structural relaxation time/same viscosities, the samples prepared by compression of liquid at high temperatures have significantly elongated induction times as well as overall crystallization times (sample 2: t(0) approximately = 4 h, t(1/2) approximately = 37.5 h; sample 3: t(0) approximately = 5.6 h, t(1/2) approximately = 49 h) compared to that held at lower temperature and ambient pressure (sample 1: t(0) approximately = 1.2 h, t(1/2) approximately = 12.2 h). A possible explanation of this finding is also given.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemistry , Ibuprofen/chemistry , Pressure , Crystallization , Kinetics , Temperature
15.
J Pharm Sci ; 99(2): 828-39, 2010 Feb.
Article in English | MEDLINE | ID: mdl-19593787

ABSTRACT

Verapamil hydrochloride (VH) is a very popular calcium channel blocker. Solubility of its crystalline form in the blood reaches only 10-20%. Thus, it seems to be very important to improve its bioavailability. In this article, we show that the preparation of the amorphous form of VH enhance its dissolution rate. In addition we performed dielectric measurements to describe molecular dynamics of this active pharmaceutical ingredient (API). Since examined sample is typical ionically conducting material, to gain information about structural relaxation we employed the dielectric modulus formalism. The temperature dependence of the structural relaxation time can be described over the entire measured range by a single Vogel-Fulcher-Tamman (VFT) equation. From the VFT fits the glass transition temperature was estimated as T(g) = 320.1 K. Below glass transition temperature one clearly visible secondary relaxation, with activation energy E(a) = 37.8 kJ/mol, was reported. Deviations of experimental data from KWW fits on high-frequency flank of alpha-peak indicate the presence of an excess wing in tested sample. Based on Kia Ngai's coupling model we identified the excess wing as true Johari-Goldstein process.


Subject(s)
Calcium Channel Blockers/chemistry , Verapamil/chemistry , Algorithms , Analgesics, Opioid/chemistry , Biological Availability , Calcium Channel Blockers/administration & dosage , Calorimetry, Differential Scanning , Chemistry, Pharmaceutical , Crystallization , Dosage Forms , Electrochemistry , Molecular Conformation , Solubility , Spectrophotometry, Ultraviolet , Spectrum Analysis , Temperature , Tramadol/chemistry , Verapamil/administration & dosage , X-Ray Diffraction
16.
J Pharm Sci ; 99(1): 94-106, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19475556

ABSTRACT

Dielectric relaxation measurements as well as differential scanning calorimetry and X-ray diffraction investigations were performed on tramadol monohydrate and its hydrochloride salt. Examined samples do not crystallize during cooling and in consequence they reach the glassy state. In the case of the hydrochloride tramadol we are able to monitor alpha-relaxation process despite large contribution of dc conductivity to the loss spectra. It is the first such study on the salt of the drug. Up to now the dielectric spectroscopy has been regarded as useless in measuring such kind of API (active pharmaceutical ingredient). In this paper we also made some suggestions about the nature of the secondary relaxations in the amorphous tramadol monohydrate and its salt. The knowledge about the molecular mechanisms, which govern the observed secondary relaxations seems to be the key in predicting the stability of the amorphous form of the examined API. Finally additional dissolving measurements on the amorphous and crystal tramadol hydrochloride were performed. As a result we understood that dissolution properties of the amorphous form of the considered drug are comparable to those of crystalline one. However, we have found out that amorphous tramadol hydrochloride has greater ability to form tablets than its crystalline equivalent. This finding shows that amorphous drugs can be alternative even for the freely solved pharmaceuticals such as tramadol hydrochloride, because the former one has better ability to form tablets. It implies that during tabletting of the amorphous drugs there is no need to use any excipients and chemicals improving compaction properties of the API.


Subject(s)
Analgesics, Opioid/chemistry , Chemistry, Pharmaceutical , Tramadol/chemistry , Calorimetry, Differential Scanning , Crystallization , Drug Compounding , Electric Conductivity , Molecular Structure , Phase Transition , Solubility , X-Ray Diffraction
17.
Pharmazie ; 63(10): 731-5, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18972835

ABSTRACT

The influence of pellet core ingredients on pellet behaviour, e.g. during compression, is well known. In this study the influence of components of a Kollicoat SR polymer film on mechanical properties was investigated. The aim of this study was to evaluate the influence of polymer film components on the mechanical properties of the pellet as a whole, from the point of view of tableting. Tablets should disintegrate into undeformed pellets floating in this environment for 5-6 h, releasing the model drug--verapamil hydrochloride--if possible in a controlled way. The usefulness of texture analysis and work of compression measurement was also evaluated. Kollicoat SR in the form of a 30D aqueous dispersion was chosen as the main component of the polymer film. Polyvinyl pyrrolidone K-30 as a pore former, and propylene glycol, triethyl citrate and dibutyl sebacate plasticisers were selected as typical additives. The influence of different thickness of polymer film on behaviour during stress was also evaluated. After coating the cores with a 20 microm Kollicoat SR dispersion film, an increase in mechanical strength, in comparison to the pellet core, was observed (2.74 to 3.34 mJ). Addition of porophor increased the work of compression by 50% to 5.1 mJ. The investigation of the influence of plasticiser on film properties proved that the kind of plasticiser used in the polymer film had no effect on the mechanical properties of the film or pellets. Only in the case of the film with triethyl citrate was no distinct of the pellet core found. Pellets coated both with films with triethyl citrate and with dibutyl sebacate, in contrast to pellets with a film coating with propylene glycol, showed a significant decrease of the dissolution rate of verapamil hydrochloride (20, 10 and 40% at 6 hours, respectively). It is possible to compress pellets with a 50 microm polymer film without affecting the dissolution rate, as was confirmed during release studies. When using Kollicoat SR the most appropriate plasticizer seems to be triethyl citrate, and in this case a change of behavior during compression analysis by texture analyzer was observed. But so relationship was found between the type of plasticizer and the work needed to obtain a given deformation.


Subject(s)
Polyvinyls/chemistry , Biological Availability , Calcium Channel Blockers/administration & dosage , Calcium Channel Blockers/chemistry , Calcium Channel Blockers/pharmacokinetics , Chemistry, Pharmaceutical , Delayed-Action Preparations , Drug Compounding , Hardness , Microscopy, Electron, Scanning , Particle Size , Plasticizers , Tablets , Verapamil/administration & dosage , Verapamil/chemistry , Verapamil/pharmacokinetics
18.
Ann Oncol ; 15(8): 1222-30, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15277262

ABSTRACT

BACKGROUND: The reported probability of survival of patients with Hodgkin's disease (HD) following high-dose chemotherapy with autologous stem cell transplantation (HDC/ASCT) is 35-65% at 5 years. The Polish Lymphoma Research Group investigated retrospectively prognostic factors for overall survival (OS) and event-free survival (EFS), and the risk of secondary malignancies in a large series of patients who underwent HDC/ASCT. PATIENTS AND METHODS: The data of 341 consecutive patients treated in 10 centers from 1990 to 2002 were collected and analyzed. RESULTS: The actuarial 5-year OS and EFS were 64% [95% confidence interval (CI) 57% to 71%] and 45% (95% CI 39% to 51%), respectively. In the multivariate model, unfavorable prognostic factors for EFS were less than partial response at the time of ASCT [relative risk (RR), 2.92 (95% CI 1.68-5.08); P<0.001] and three or more previous chemotherapy lines (RR, 2.16; 95% CI 1.42-3.30; P<0.001). These two factors were also associated with unfavorable OS (RR, 3.32; 95% CI 1.90-5.79; P<0.001 and RR, 2.34, 95% CI 1.51-3.64; P<0.001). Five-year cumulative risk of secondary malignancy was 8.4% (95% CI 2% to 13%) and the only identified risk factor was splenectomy (P=0.02). CONCLUSIONS: HDC/ASCT should be considered early in the course of disease for patients with a response after standard therapy.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Hodgkin Disease/drug therapy , Stem Cell Transplantation , Adolescent , Adult , Child , Child, Preschool , Disease-Free Survival , Dose-Response Relationship, Drug , Female , Humans , Male , Middle Aged , Neoplasms, Second Primary , Prognosis , Retrospective Studies , Risk Factors , Transplantation, Autologous , Treatment Outcome
19.
Eur J Gynaecol Oncol ; 24(5): 413-6, 2003.
Article in English | MEDLINE | ID: mdl-14584659

ABSTRACT

OBJECTIVE: The aim of study was to estimate of the value of fine needle aspiration biopsy (FNAB) and transvaginal ultrasonography (TVS) in the preoperative assessment of the parametria in cervical cancer. We compared parametrial infiltration before and postoperatively by histopathology to verified and confirmed staging of disease. Correct staging qualification, especially evaluation of the parametrium, is very useful in choosing an adequate method of treatment, and thereby in patient survival. MATERIAL AND METHOD: 52 women (median age 56 years, range 33-85) with cervical cancer in Stage Ib and 49 (median age 51, range 36-71) in Stage II and III, were included in the study. Assessment of parametrial invasion before treatment was performed by fine needle aspiration biopsy (FNAB) with endovaginal ultrasound assistance. The sonographic evaluation of parametria was performed by Siemens Sonoline Versa Pro with a transvaginal 7 MHz mechanical transducer with a biopsy guide and 21-gauge needle. The probe was covered with a disposable latex sheath filled with ultrasound gel. The aspirated material was placed on a glass slide, fixed in 95% alcohol and submitted to cytologic evaluation. All of the patients with cervical cancer in Stage Ib underwent a Wertheim-Meigs hysterectomy. The preoperative findings were compared with data obtained by histopathology findings. Moreover, in the whole group of 101 patients a comparison of FNAB and sonography was performed. The sensitivity, specificity and diagnostic accuracy of this method were evaluated. RESULTS: Parametrial involvement assessed postoperatively by histopathology, in clinical Stage Ib cervical cancer was found in eight of 52 cases (15.4%). FNAB of parametrial involvement in the operated group was accurate in 14 of 18 (accuracy--83%, sensitivity--78%, specificity--84%, PPV--50%, NPV--95%). Sonographic assessment of parametrial involvement was correct in 12 of 18 cases (accuracy--58%, sensitivity--67%, specificity--56%, PPV--24%, NPV--89%). In the whole group of patients (operated and non-operated), sonographic evaluation of parametria verified by FNAB was correct in 104 of 202 cases (accuracy--78%, sensitivity--71%, specificity--86%, PPV--84%, NPV--74%). CONCLUSIONS: FNAB and TVS assessment of the parametria are very useful methods in confirmation of neoplastic infiltration. Correct preoperative diagnosis may improve staging, treatment and indirectly, survival of patients with cervical cancer.


Subject(s)
Biopsy, Fine-Needle , Carcinoma, Squamous Cell/pathology , Uterine Cervical Neoplasms/pathology , Adult , Aged , Aged, 80 and over , Carcinoma, Squamous Cell/diagnostic imaging , Carcinoma, Squamous Cell/surgery , Female , Humans , Middle Aged , Neoplasm Invasiveness , Predictive Value of Tests , Sensitivity and Specificity , Ultrasonography , Uterine Cervical Neoplasms/diagnostic imaging , Uterine Cervical Neoplasms/surgery
20.
Eur J Gynaecol Oncol ; 24(3-4): 293-8, 2003.
Article in English | MEDLINE | ID: mdl-12807243

ABSTRACT

OBJECTIVE: To determine the efficiency of transabdominal and transvaginal ultrasonography (TAS and TVS) in the assessment of myometrial invasion, cervical involvement, pelvic lymph nodes, adnexal and omental metastases (preoperative staging) of endometrial cancer. METHODS: Transabdominal and transvaginal 2D, ultrasound were performed on 90 women to classify myometrial invasion, cervical involvement, pelvic lymph nodes and adnexal metastases in endometrial cancer. According to this 13 type E (invasion involving the endometrium), 41 type S (superficial, of less than 50% of myometrial infiltration), 36 type D (deep infiltration) and 22 cervical involvement were identified. There were 15 G1, 60 G2 and 15 G3 cases. Adnexal, omental and lymph-node metastases were found in 11, two and 15 cases, respectively. Endometrial cancer was diagnosed on the basis of dilatation and curettage. The degree of invasion was evaluated preoperatively. Ultrasonographic findings were compared to surgical staging and histopathology of the surgical specimen. RESULTS: The median age of the 90 women was 63.3 +/- 12.3 years (range 32 to 86 years). The median thickness of malignant endometrium was 19.5 +/- 9.6 (range 7 to 54 mm). In type E the median thickness was 11.76 +/- 4.2, in type S 17.3 +/- 7.6, in type D 24.8 +/- 9.8 and in cases with cervical involvement 23.2 +/- 11 mm. Myometrial invasion evaluated by TVS was accurate in 76 of 90 cases (accuracy 84.4%). In type E sensitivity was 92.3%, specificity 87.0%, positive and negative predictive value, respectively, 63.1% and 98.6%. In type S these values were respectively: 78.0%, 93.9%, 91.4%, 80.0% and in type D--88.9%, 92.6%, 88.9% and 100.0%. Tumor extension to the cervix was properly assessed in 19 of 22 women in which it was present (sensitivity 86.4%, specificity 85.3%, positive predictive value 85.5%, negative predictive value 95.1%). Adnexal metastasis was correctly diagnosed in 8 of 11 cases in which it was present (sensitivity 72.7%, specificity 97.5%, positive predictive value 80%, negative predictive value 96.3%), and lymph-node metastasis in only 5 of 15 cases (sensitivity 33.3%, specificity 100%, positive predictive value 100%, negative predictive value 88.2%). CONCLUSION: These results suggest that 2D TAS and TVS evaluation of endometrial cancer are reliable methods for preoperative assessment of selected prognostic factors, e.g. myometrial invasion, cervical involvement and adnexal metastases. However in assessing lymph-node metastases, TVS with its low sensitivity, did not provide additional information. Preoperative ultrasound examination should be speculated as an important tool in the establishment of different surgical choices which can be made after a correct pretreatment prognosis.


Subject(s)
Endometrial Neoplasms/diagnostic imaging , Endometrial Neoplasms/pathology , Endosonography/methods , Lymph Nodes/pathology , Neoplasm Invasiveness/diagnostic imaging , Neoplasm Invasiveness/pathology , Adult , Aged , Aged, 80 and over , Biopsy, Needle , Cohort Studies , Endometrial Neoplasms/mortality , Female , Humans , Hysterectomy/methods , Middle Aged , Neoplasm Staging , Predictive Value of Tests , Preoperative Care/methods , Prognosis , Retrospective Studies , Risk Assessment , Sensitivity and Specificity , Survival Analysis , Treatment Outcome , Vagina
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