# Evidence: kinetic barrier to nucleation

Parent: — · class: kinetics · names merged here: activation energy for nucleation; kinetic barrier to nucleation

2 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.

## 2006 Konno — Influence of Different Polymers on the Crystallization Tendency of Molecularly Dispersed Amorphous Felodipine · Solid state stability / Physical stability

[2006-konno-felodipine-polymer-crystallization-nucleation-solid-dispersions](../../../cards/2006-konno-felodipine-polymer-crystallization-nucleation-solid-dispersions/paper.html) · Solid state stability / Physical stability · used · as: kinetic barrier to nucleation

| id | kind | content | locator |
|---|---|---|---|
| E8 | equation | classical nucleation rate (Turnbull-Fisher): I = A·exp[−(ΔG* + ΔGa)/kT] | p.2702 |
| C36 | claim, mechanism, authors: "can potentially" | The polymer can raise ΔGa (drug diffusion across the interface) as a diluent, through specific interactions with the drug, or by accumulating at the nucleus-amorphous matrix interface [rests on: argument only; cited: refs 39, 44] | p.2703 |
| C40 | claim, mechanism, authors: discussion: "it seems reasonable to speculate"; abstract and conclusions: "It was speculated" | The polymers increase the magnitude of ΔGa, with a consequent decrease in nucleation and growth rates; abstract and conclusions: speculated that the polymers reduce the nucleation rate by increasing the kinetic barrier to nucleation [rests on: R4; argument only] | p.2692, p.2703 |
| C41 | claim, generalisation, authors: "it appears"; "consistent with"; conclusions: "It was speculated" | After the initial large drop with a small amount of polymer, the polymer effect on ΔGa is related to the amount of polymer and, for these three polymers, relatively independent of polymer type, consistent with a physical impediment to drug transport at the nucleus-matrix interface in which polymer volume fraction is the controlling parameter; conclusions: scale of the effect related to polymer concentration and independent of the polymers' physicochemical properties [rests on: R4] | p.2703 |

## 2006 Marsac — A Comparison of the Physical Stability of Amorphous Felodipine and Nifedipine Systems · Solid state stability / Physical stability

[2006-marsac-physical-stability-amorphous-felodipine-nifedipine](../../../cards/2006-marsac-physical-stability-amorphous-felodipine-nifedipine/paper.html) · Solid state stability / Physical stability · measured · as: activation energy for nucleation

| id | kind | content | locator |
|---|---|---|---|
| R3 | record, derived (E2) | activation energy for nucleation ΔE (kJ/mol), SD in parentheses, n = 3 — pure amorphous drugs and dispersions with 3 wt% PVP, from Fig. 3 (R2) — sub-table below; text: drugs not statistically different above Tg; felodipine significantly higher below Tg; increase with 3% PVP statistically significant for felodipine below Tg and nifedipine above Tg, not significant for felodipine above Tg and nifedipine below Tg; statistical test not named | Table I, p.2309; text p.2309-2310, p.2314 |
| E2 | equation | Arrhenius equation for nucleation rate: I = A exp(−ΔE/RT) | p.2307 |
| C9 | claim, conclusion, authors: asserted ("significantly greater") | ΔE of the two pure drugs is not statistically different above Tg, whereas below Tg ΔE of felodipine is significantly greater than that of nifedipine [rests on: R3.a-b] | p.2309 |
| C48 | claim, conclusion, authors: "it appears" | Below Tg the felodipine-PVP dispersion has a higher ΔE than the nifedipine dispersion, so the energetic barrier for nucleation appears higher for felodipine with and without polymer [rests on: R3] | p.2314 |