Solid State Characterization of Dehydroepiandrosterone

Chang, Luh‐Chian; Caira, Mino R.; Guillory, J. Keith

doi:10.1002/jps.2600841007

Cited by 26 publications

(18 citation statements)

References 9 publications

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“…This indicates that the melting process of metastable lower melting forms and the crystallization of the higher melting forms take place simultaneously. In order to give an insight into the stability relationship of monotropic polymorphic pairs and to find their virtual temperature of transition, enthalpy of solution method along with the solubility (32)(33)(34)(35)(36)(37)(38)(39) are utilized in the present study. The enthalpy of transition (ΔH (T)), free energy of transition (ΔG(T)) and entropy of transition (ΔS(T)) accompanying the transition of lower melting form to higher melting form are determined at 25°, 37° and 50° using the following equations and are given in Table 3.…”

Section: Estimationmentioning

confidence: 99%

An Insight into Thermodynamic Relationship Between Polymorphic Forms of Efavirenz

Chadha

Arora²,

Saini³

et al. 2012

J Pharm Pharm Sci

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-Purpose:The aim of the work is to study the crystallization of efavirenz to understand the preferential formation of various polymorphic forms, to establish their identity, to study the transformation between the polymorphic forms on heating and to determine their free energy. Methods: Slow crystallization from different solvents under controlled conditions was employed to prepare various crystalline forms. The TGA and DSC were used to study their thermal behavior and inter-conversion of these forms. The calorimetrically determined enthalpies of solution and solubility data are utilized to determine the transition temperatures. Results: Six polymorphic forms of efavirenz are identified and characterized completely. The TGA scans of all the forms did not show any mass loss indicating absence of hydrate or solvate. The thermally induced transformations are observed in the DSC scans of five forms II-VI indicating them to be metastable which are converted to stable higher melting forms. The melting temperature and enthalpy of fusion of lower melting (Form L ) and higher melting forms (Form H ) reveal that four of these polymorphic pairs are monotropically related. The enthalpies of solution of Form L are found to be more exothermic as compared to corresponding Form H . The transition temperature (T t ) determined using enthalpy of solution and solubility data was found to be higher than the melting of both the forms except for polymorphic pair VI L /VI H . The effect of ΔC p on transition temperature is also reported. Conclusions: The form I is found to be thermodymanically most stable but least soluble. The forms II-V are metastable and are converted irreversibly to stable forms. The enthalpy of fusion rule and virtual transition temperature provided complementary evidence for the existence of monotropy in these polymorphic pairs. However, enantiotropy is demonstrated in VI L /VL H pair and is well established in our study. Novelty: The present study reveals the thermodynamic aspects of various isolated polymorphic forms of efavirenz. Solution calorimetry along with other techniques is used to study the transformation of one form to another. The emphasis is laid on determination of transition temperature of various polymorphic pairs which has not been reported earlier.

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Section: Estimationmentioning

confidence: 99%

An Insight into Thermodynamic Relationship Between Polymorphic Forms of Efavirenz

Chadha

Arora²,

Saini³

et al. 2012

J Pharm Pharm Sci

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“…In this particular example, the transformation rate for conversion of Form B to Form A decreases with the ethanol concentration. Form I of dehydroepiandrosterone was obtained by recrystallization from a mixture of warm ethyl acetate, acetone and acetonitrile [20]. The new triclinic form B of hydroxyprogesterone caproate was synthesized from slurry in multiple solvent [21].…”

Section: Art Of Synthesis Of Desired Polymorphs: a Reviewmentioning

confidence: 99%

Art of Synthesis of Desired Polymorphs: A Review

Tandon¹,

Tandon²,

Gupta³

2017

Asian J. Chem.

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Polymorphism plays an important role in drug solubility and availability. The study of the polymorphism of active pharmaceutical ingredients has become crucial for the synthesis of active pharmaceutical ingredients. This review provides observations, synthetic methods and characterization techniques for polymorphs using the latest analytical techniques. The desired polymorph can be obtained by choosing the proper nucleation mechanism.

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“…DHEA has eight different polymorphic forms. Six crystalline forms of DHEA (FI−FVI) were described [ 18 , 19 ], and the forms FVII and FVIII have been described previously [ 14 ]. In the present study, we analyze the mechanism of formation of nanoparticles, its connection with the formation of polymorphous nanostructures, the synthesis of the latter as a function of the nature of carrier gas, and the temperature of cryochemical synthesis.…”

Section: Introductionmentioning

confidence: 99%

Cryochemical Synthesis of Polymorphous Nanostructures of a Steroid Neurohormone

et al. 2017

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A new cryochemical strategy of producing nanoparticles and polymorphous nanostructures of drugs is used, which is based on the dynamic combination of high and low temperatures, gas and solid phases, and inert carrier gases. This technology is applied to the synthesis of nanoparticles of steroid neurohormone dehydroepiandrosterone (DHEA). We have optimized the conditions of synthesis of the new polymorphous DHEA structure, FVII. The molecules of DHEA in FVII structure are bound by hydrogen bonds via oxygen atoms. The grain size is 100 nm. It is shown that the yield and ratio of the resulting nanoforms of this hormone are determined by the nature and properties of the inert carrier gas. The highest yield and selectivity of FVII are observed when carbon dioxide is used as the carrier gas. In the case of helium, the FVII content decreases from 85 to 30% and other structures are formed. In experiments without carrier gas, nanoparticles are formed but no FVII is produced. The selectivity and the effect of carrier gas are considered on the basis of homogeneous and heterogeneous formation of nanoparticles and the relationship between particle selectivity and its activity. The synthesis of various polymorphous structures on the nanoscale is assumed to be the manifestation of the size effect in the synthesis of drugs.

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Solid State Characterization of Dehydroepiandrosterone

Cited by 26 publications

References 9 publications

An Insight into Thermodynamic Relationship Between Polymorphic Forms of Efavirenz

An Insight into Thermodynamic Relationship Between Polymorphic Forms of Efavirenz

Art of Synthesis of Desired Polymorphs: A Review

Cryochemical Synthesis of Polymorphous Nanostructures of a Steroid Neurohormone

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