# Evidence: single-Tg miscibility criterion

Parent: — · class: measurement · names merged here: single glass transition as a miscibility criterion; single glass transition criterion for miscibility; single-Tg criterion of miscibility; single-Tg miscibility criterion

4 papers measured or used it, 0 only mentioned it (of 207 kept papers). Papers in year order; each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/concepts.csv and the cards; do not edit.

## 2009 Rumondor — Evaluation of Drug-Polymer Miscibility in Amorphous Solid Dispersion Systems · Solid state stability / Miscibility and drug-polymer interactions

[2009-rumondor-drug-polymer-miscibility-asd-dsc-ir-pxrd](../../../cards/2009-rumondor-drug-polymer-miscibility-asd-dsc-ir-pxrd/paper.html) · Solid state stability / Miscibility and drug-polymer interactions · used · as: single-Tg criterion of miscibility

| id | kind | content | locator |
|---|---|---|---|
| C5 | claim, assumption, authors: "commonly inferred"; "is indicative of" | In DSC a single Tg is taken to mean one amorphous phase and more than one Tg more than one phase; DSC is considered the "golden standard" [rests on: cited: ref 15] | p.2525 |
| C6 | claim, caveat, authors: "may result"; "could result"; "may not provide" | DSC has inherent limits: domains below 15-30 nm may give no two distinct Tgs; the changing temperature could shift miscibility during the scan; a single Tg above the lowest component Tg may not establish the number of phases at room temperature [rests on: R25; argument only] | p.2525 |
| C17 | claim, conclusion, authors: "reasonable agreement"; "suggest" | Ketoconazole-PVP shows a single Tg at every composition, in reasonable agreement with Couchman-Karasz and consistent with the literature, which points to molecular-level mixing [rests on: R3, R4, R5] | p.2526 |
| R25 | record, cited (refs 15, 20) | detection limit of DSC for phase separation — binary amorphous mixtures — domains smaller than 15-30 nm may give no two distinct Tg events | p.2525 |

## 2012 Eerdenbrugh — Molecular Weight Effects on the Miscibility Behavior of Dextran and Maltodextrin with Poly(vinylpyrrolidone) · Solid state stability / Miscibility and drug-polymer interactions

[2012-van-eerdenbrugh-dextran-maltodextrin-pvp-molecular-weight-miscibility](../../../cards/2012-van-eerdenbrugh-dextran-maltodextrin-pvp-molecular-weight-miscibility/paper.html) · Solid state stability / Miscibility and drug-polymer interactions · used · as: single glass transition criterion for miscibility

| id | kind | content | locator |
|---|---|---|---|
| P3 | method | DSC glass transition and miscibility classification | p.2756-2757, p.2761 |
| C3 | claim, prior hypothesis, authors: asserted; heating effect "may have an effect" | DSC infers miscibility from a single Tg event and phase separation from two, but similar component Tgs, the minimum detectable domain size (R18), broad transitions or small heat-capacity steps can defeat it, and heating through the Tg region may change a temperature-dependent miscibility; complementary techniques are therefore an important research area [rests on: cited: refs 4, 6, 7; R18] | p.2755 |
| C11 | claim, conclusion, authors: "These results suggest"; all grades: asserted ("Hence") | The single Tg of DEX1-PVP25, rising with PVP25 content, suggests a miscible system over the complete composition range; with similar behaviour for the other PVP grades, PVP is miscible with DEX1 for all grades and compositions [rests on: R1, R3] | p.2757 |

## 2015 Purohit — Miscibility of Itraconazole-Hydroxypropyl Methylcellulose Blends- Insights with High Resolution Analytical Methodologies · Solid state stability / Miscibility and drug-polymer interactions

[2015-purohit-itraconazole-hpmc-miscibility-high-resolution-methods](../../../cards/2015-purohit-itraconazole-hpmc-miscibility-high-resolution-methods/paper.html) · Solid state stability / Miscibility and drug-polymer interactions · measured · as: single glass transition as a miscibility criterion

| id | kind | content | locator |
|---|---|---|---|
| R7 | record, measured | glass transition onset, midpoint and offset (°C), reversing heat flow — rotary-evaporated powders (P7), modulated DSC first and second heating (P8) — sub-table below; one Tg step per composition in both runs | Table 2, p.31; text p.12 |
| C22 | claim, prior hypothesis, authors: "generally considered" | A single calorimetric Tg is generally considered an indicator of drug-polymer miscibility [rests on: argument only] | p.12 |
| C23 | claim, conclusion, authors: "indicate" | The dispersions show a single midpoint Tg at all ratios, rising with polymer content, so DSC shows a miscible system at all ratios [rests on: R7, R8] | p.12 |
| C36 | claim, conclusion, authors: discussion: asserted ("clearly indicate"); abstract: "phase separation was observed"; conclusions: DSC "provided ambiguous results" | ITZ and HPMC are phase separated over 10-50% drug loading when prepared by solvent removal and examined by fluorescence spectroscopy or AFM-IR, while DSC did not show clear evidence of phase separation [rests on: R1, R6, R10, R11, R7] | p.2; p.14; p.19 |
| C40 | claim, prior hypothesis, authors: asserted | DSC has given ambiguous miscibility results in several earlier cases, including HPMC-ITZ [rests on: cited: refs 36, 59] | p.15 |

## 2017 Purohit — Insights into Nano- and Micron-Scale Phase Separation in Amorphous Solid Dispersions Using Fluorescence-Based Techniques in Combination with Solid State Nuclear Magnetic Resonance Spectroscopy · Characterization methods / Solid-state methods

[2017-purohit-itraconazole-hpmc-asd-phase-separation-fluorescence-ssnmr](../../../cards/2017-purohit-itraconazole-hpmc-asd-phase-separation-fluorescence-ssnmr/paper.html) · Characterization methods / Solid-state methods · measured · as: single-Tg miscibility criterion

| id | kind | content | locator |
|---|---|---|---|
| R3 | record, measured | glass transition (reversing heat flow, mDSC 2°C/min) — SD ASD (trace a) and rotary-evaporated ASD (trace b) (P6) — one broad Tg step per sample; text: mid-point Tg 87°C for both samples; Fig. 3 arrows at ≈90°C (a) and ≈88°C (b) (read from Fig. 3) | Results, pdf p.5; Fig. 3, pdf p.5 |
| R7 | record, measured | pyrene I1/I3 peak ratio (Table I, sub-table below) — ITZ alone, HPMC alone and 40:60 ASDs, excitation 332 nm (P9) — rows a–e below; standard deviations ≤0.02 for all samples; n not printed | Table I, pdf p.6; Results, pdf p.6 |
| C25 | claim, mechanism, authors: Introduction: often provides ambiguous; Discussion: can potentially lead | A single DSC Tg is an ambiguous miscibility criterion: besides a 15–30 nm resolution limit, heating towards Tg raises mobility and miscibility, which can remix a phase-separated ASD and yield one Tg although it was partially miscible or immiscible at ambient conditions. [rests on: R28, R29, R30; cited: refs 14, 15] | Introduction, pdf p.2; Discussion, pdf p.10 |
| C26 | claim, conclusion, authors: asserted | In this study DSC gave a single, broad Tg for all ASDs studied (miscible by DSC criteria), whereas the fluorescence techniques detected phase separation in all samples. [rests on: R3, R7, R16, R17] | Discussion, pdf p.10; Conclusions, pdf p.12 |