Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: H. Stulzer x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Primaquine (PQ) is the drug of choice for the radical cure of Plasmodium vivax malaria, and currently being administered in solid dosage form. In this study, the compatibility studies were carried out using differential scanning calorimetry (DSC), thermogravimetry (TG), and fourier transformed infrared (FT-IR). Non-isothermal and isothermal methods were employed to investigate kinetic parameters under nitrogen and air atmospheres using TG. The DSC investigations obtained by physical mixtures showed slight alterations in the melting temperatures of PQ with some excipients. The FT-IR confirmed the possible interactions obtained by DSC for the physical mixtures with PQ and lactose, magnesium stearate and mannitol. The results showed that the thermal decomposition followed a zero order kinetic in both atmospheres in non-isothermal method. The activation energy in both methods using nitrogen atmosphere was similar, and in air atmosphere the activation energy decreased.

Restricted access

Abstract  

Captopril (CAP) was the first commercially available angiotensine-converting enzyme (ACE) inhibitor. In the anti-hypertensive therapy is considered the selected drug has to be therapeutically effective together with reduced toxicity. CAP is an antihypertensive drug currently being administered in tablet form. In order to investigate the possible interactions between CAP and excipients in tablets formulations, differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis completed by X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR) were used for compatibility studies. A possible drug-excipient interaction was observed with magnesium stearate by DSC technique.

Restricted access

Sibutramine hydrochloride monohydrate

Thermal behavior, decomposition kinetics and compatibility studies

Journal of Thermal Analysis and Calorimetry
Authors: P. Oliveira, H. Stulzer, L. Bernardi, S. Borgmann, S. Cardoso, and M. Silva

Abstract  

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.

Restricted access