News & Trends for Thermal Analysis

Transcription

1 Vietnam, October 2016 VõĐình Vũ News & Trends for Thermal Analysis Pharma Applications and Theory

2 TA-Techniques DSC, Flash DSC, HPDSC TGA TMA DMA

3 Agenda Compatibility and Interactions - Eutectic Systems - Compatible/Incompatible Mixtures Shelf life prediction - Decomposition dynamics - Kinetics of shelf life Overview - Polymorphism - Purity - Sorption/Desorption - Packaging material

4 Interaction and compatibility 4 Are you interested in the study of compatibility between the active pharmaceutical ingredient and the excipient in the formulation? The interaction between two or more components of a pharmaceutical preparation can be desirable or undesirable. Desirable interactions are purposely brought about in order to improve the solubility of an active ingredient. Undesirable interactions, i.e. incompatibility, can bring about a loss of activity or even a complete deactivation of a preparation. Even toxic decomposition products can be produced in the most unfavorable cases.

5 Interaction and compatibility 5 Principle: Pharmaceutical preparations can be investigated by DSC or TGA by comparing the results for the individual components and the mixture with each other. If the mixture exhibits thermal effects that are not apparent in the individual components, which indicates of an interaction. A eutectic system, however, shows thermal changes which are not caused by incompatibility. In real situation, the exposure of drug-excipient mixture to high temperatures is not experienced by the dosage form, therefore, the results should be interpreted carefully together with other test results e.g. Isothermal stress testing (IST)

6 Phase Diagram Binary phase diagram T T 0A crystals A + liquid liquid solution crystals B + liquid liquidus line Example A: Benzoic acid T 0B B: Dimethylterephthalate crystals A + crystals B solidus line 0 x B 1

7 Phase Diagram Binary phase diagram ^exo Pharma: D MT/benz oic acid :21:09 4 % BA Onset C Onset C 50 mw 7 % BA 13 % BA 48 % BA 62 % BA 89 % BA Onset C Onset C Onset C Onset C Onset C Pure DMT Onset C DMT: Dimethylterephthalate Benzoic acid Eutectic mixture: 28 mol% DMT Pure benzoic acid C TA MSG31: R. Riesen METTLER TOLEDO O STA TAR e System

8 Phase Diagram Binary phase diagram DMT: Dimethylterephthalate Benzoic acid Eutectic mixture: 28 mol% DMT

9 Interaction and compatibility 9 Compatibility between acetyl salicylic acid & Avicel 2 Wg^ *!&Avicel 2nd+0.74*!&Aspirin Integral mj normalized Jg^-1 Onset C 2. Heating 1. Heating Integral mj normalized Jg^-1 Onset C 73.7% ASA Aspirin/Avicel2, mg Mixture Aspirin 1000mg : Avicel 268mg Avicel pure ph mg Aspirin, mg pure ASA Sample Holder: Aluminum Standard 40ul with pierced lid Method: D /5 al std air C 5.00 C/min Nitrogen Acetyl salicylic acid Avicel PH: microcrystalline cellulose, inactive excipient for direct compression formulations, lending superior compatibility and carrying capacity to tablets C

10 Interaction and compatibility

11 Interaction and compatibility The mixture shows only one melting peak at much lower temperature compared to the pure components, indicates incompatibility due to strong interactions.

12 Shelf Life 12 Are you interested in a rapid method to determine the shelf life of your products? Acetylsalicylic acid: used to relieve pain and reduce fever and inflammation.

13 Kinetics/Reaction Dynamics 13 n-th Order Kinetics Single dynamic measurement Calculation of kinetic parameters k 0, E and n from one single dynamic measurement with multiple linear regression (n th order kinetics): dα = dt E / RT k0 e (1 α ) Multiple dynamic measurements n The so called iso-conversional methods are based on several measurements using different heating rates. Kissinger, Ozawa (ASTM E698) use the temperature of the peak maximum, Flynn-Wall (ASTM E1641).

14 Kinetics/Reaction Dynamics 14 n-th Order Kinetics A B C A B C A B + C??? autocatalytic reactions competing, consecutive reactions diffusion,

15 Kinetics/Reaction Dynamics 15 complex reactions dα = d q t p= 1 f ( α) f ( α) f ( α) f ( α) etc. f p = (1 α) = = = ( α) k n p ( T ) 1 ( ln( 1 α )) [ ( ) ] 1/3 1 3/ 21 1 α n( 1 α )( ln( 1 α )) ( n 1)/ n Large number of parameters Practical no differences between differnt models The apparent activation energy is a function of conversion alternatively: Model Free reaction dynamic no explicit model functions have to be assumed

16 Kinetics/Reaction Dynamics 16 Reaction Dynamic Model Free Kinetics Isoconversional method reaction rate at a certain conversion = f(t) Use of Arrhenius temperature function Complex chemical reactions (e.g. with transport phenomena) show an activation energy that depends on the conversion The resulting activation energy as a function of conversion is the basis of predictions

17 Kinetics/Reaction Dynamics 17 Model Free Kinetics Separation of the variables in the rate equation and integration with respect to t delivers g(α): α d α = k (T ) f ( α ) g( α ) = 1 d t 0 f ( α ' ) tα d α ' = k d t t0 Insertion of Arrhenius equation and of the definition of β: g ( α ) k 0 β T = α 0 exp E ( α RT ) d T g(α) is assumed to be independent of β. Based on several experiments with different heating rates β i one finally has to solve numerically (Vyazovkin): k k g( α 0 0 ) = I( E α,tα, β ) = I( E α,tα, β ) =... 2 β β = 1 k 0 β I( E 1 α α, 2 n I(E α,t α,β ),T β n )

18 Shelf Life - Stability Decomposition kinetics ^exo 1 mg TGA Curves 2 C Pharma: Acetylsalicylic Acid :29:54 SDTA Curves 10 K/min, mg 5 K/min, mg 2 K/min, mg 1 K/min, mg mg C^ Acetylsalicylic acid: TGA measurement for kinetic purpose DTG Curves C TA MSG31: R. Riesen METTLER TOLEDO STA TAR System e

19 Stability Storage conditions Pharm a: Kinetics, Prediction :13:30 % Conversion Curves kjm ol^ Activation Energy Applied Kinetics: Iso-Conversion [ C] 1 % 2 % 10e+03 h e+03 h e+03 h h C alpha(1%) alpha(3%) alpha(2%) alpha(5%) Acetylsalicylic acid: Model free kinetics for stability predictions 50 % C TA MSG31: R. Riesen METTLER TOLEDO STA TAR e System

20 Agenda Compatibility and Interactions - Eutectic Systems - Compatible/Incompatible Mixtures Shelf life prediction - Decomposition dynamics - Kinetics of shelf life Overview - Identification/Polymorphism - Purity - Decompostion - Sorption/Desorption - Packaging material

21 Identification Purity DSC Purity: Melting point depression Van t Hoff ASTM E928

22 Polymorphism liquid liquid high temperature modification (β) stable modification monotropic transition (exothermic) low temperature modification (α) metastable modification Enantiotropic amorphous state Monotropic Vapor pressure liquid state metastable solid state II stable solid state I T fus II T fus I Temperature

23 Polymorphism Polymorphism of Chlorpropamide Chlorpropamide: antidiabetic agent. DSC is a simple and fast tool for detection of polymorphic transitions.

24 Polymorphism 24 Crystallization of chlorpropamide Crystallization temperature lower nucleation rate, less crystals higher crystal growth rate, bigger crystals Cooled from 135 C at 10 K/min and held isothermally at 80 C. Cooled from 135 C at 10 K/min and held isothermally at 90 C. Cooled from 135 C at 10 K/min and held isothermally at 100 C. Hot-stage microscope enables visual observation of polymorphic transitions.

25 Polymorphism Phase transitions Thermomicroscopy, DSC Sulfapyridine (amorphous, shock-cooled after melting)

26 Polymorphism Phase transitions ^exo Pharma: L-Polylactide :54:27 L-Polylactide mg B L-Polylactic-acid (excipient) A A: melting metastab. mod. 2 Wg^-1 Integral mj Onset C Left Limit C Right Limit C Left bl Limit C Right bl Limit C Heating Rate Cmin^-1 Baseline Type Horiz. links C B: crystallization C: melting stab. modification C TA MSG31: R. Riesen METTLER TOLEDO O STA TAR e System

27 Polymorphism 27 Pseudopolymorphism of glucose Glucose: inactive ingredient, filler for tablets and capsules

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