# Formula: surface-normalized release rate

Parent: — · class: transport, diffusion and dissolution · names as written: loading-normalized release rate; surface area and composition normalized release rate; surface normalized dissolution rate; surface normalized release rate; surface-area normalized release rate (intrinsic dissolution rate normalized to component weight fraction); surface-area-normalized release rate; surface-area-normalized release rate (rotating disk); surface-normalized dissolution rate; surface-normalized dissolution rate (intrinsic dissolution rate per component); surface-normalized release rate

15 instances in 15 papers (of 207 kept papers). Each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/formulas.csv; do not edit.

## 2018 Bhardwaj · E4 · loading-normalized release rate · Dissolution / A. Release mechanism and LoC

[2018-bhardwaj-surface-area-normalized-dissolution-itraconazole-pvpva-asd](../../../cards/2018-bhardwaj-surface-area-normalized-dissolution-itraconazole-pvpva-asd/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: release rate "normalized (to account for differences in drug and polymer content)" (stated in words; the operation is not printed)
- symbols and units: µg/min/sq cm
- assumptions stated: none stated
- used for: R11
- status: printed in words · recomputed: reproduces if the rate is divided by the component weight fraction (operation not printed): Table 2 SD drug rates ÷ drug fraction = 106, 256, 565, 1990 versus Fig. 14 bars ≈100, ≈250, ≈555, ≈2000
- locator: p.27; Fig. 14, p.28

## 2019 Saboo · E4 · surface-normalized dissolution rate · Dissolution / A. Release mechanism and LoC

[2019-saboo-congruent-drug-polymer-release-asd-sweet-spot](../../../cards/2019-saboo-congruent-drug-polymer-release-asd-sweet-spot/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: slope of linear regression of the initial linear portion of % release versus time, normalized to each component's content and to the exposed area (stated in words)
- symbols and units: mg/min/cm2; exposed area 0.50 cm2
- assumptions stated: exposed surface area constant (C8)
- used for: R5, R6
- status: printed in words · recomputed: inputs not printed (raw release data only plotted; normalization not given as a formula)
- locator: pdf p.10-11, p.19

## 2020 Li · E13 · surface normalized dissolution rate · ASD process / ASD process

[2020-li-water-induced-phase-separation-spray-dried-asd-ritonavir-pvpva](../../../cards/2020-li-water-induced-phase-separation-spray-dried-asd-ritonavir-pvpva/paper.html) · ASD process / ASD process

- expression: SNDR = slope of drug concentration versus time, normalized by the surface area of the dissolving front of the tablet and by the DL
- symbols and units: concentration from HPLC; area from 8 mm die
- assumptions stated: none stated
- used for: R10, R11
- status: printed in words · recomputed: inputs not printed (concentration-time data not shown)
- locator: p.11-12

## 2020 Saboo · E3 · surface-normalized dissolution rate · Dissolution / A. Release mechanism and LoC

[2020-saboo-asd-drug-loading-polymer-hydrophobicity-release](../../../cards/2020-saboo-asd-drug-loading-polymer-hydrophobicity-release/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: A = (k × V)/(S × N)
- symbols and units: A dissolution rate (mg/min/cm²); k slope of the regression line (mg/mL.min) not including the origin; V volume of medium (100 mL); S tablet surface area (0.5 cm²); N weight fraction of the component
- assumptions stated: weight fraction used on the assumption that component densities are similar
- used for: R13, R14, R16
- status: printed, checked against page image · recomputed: inputs not printed (regression slopes k not tabulated); plot-based check in X10
- locator: p.7

## 2020 Saboo · E1 · surface-normalized dissolution rate (intrinsic dissolution rate per component) · Dissolution / A. Release mechanism and LoC

[2020-saboo-congruent-release-hbond-crystallization-tg-pvpva-asd](../../../cards/2020-saboo-congruent-release-hbond-crystallization-tg-pvpva-asd/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V)/(S × x)
- symbols and units: R normalized release rate; k slope of the regression line of cumulative concentration versus time (µg/mL.min); V medium volume (100 mL); S exposed tablet area (0.5 cm²); x fraction of the component in the ASD
- assumptions stated: linear regression over the sampling period
- used for: R3
- status: printed, checked against page image · recomputed: inputs not printed (slopes k); plot check: neat PVPVA ≈8.5% at 5 min and ≈1.7% at 1 min of 100 mg (Fig. S2A) gives k × V ≈ 1.7 mg/min, R ≈ 3.4 mg/min/cm² versus ≈3.4 in Fig. 2A (assumes a 100 mg neat-polymer tablet, as for the ASDs)
- locator: p.8

## 2021 Yang · E1 · surface-normalized dissolution rate · Dissolution / A. Release mechanism and LoC

[2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection](../../../cards/2021-yang-asd-nanodroplet-release-drug-properties-polymer-selection/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V) / (A × x)
- symbols and units: R normalized rate of dissolution (mg min⁻¹ cm⁻², Figs. 8, 11 axes); k slope of linear regression of total concentration vs time; V volume of dissolution medium (100 mL); A exposed compact surface area (8 mm diameter die); x weight fraction of the component of interest
- assumptions stated: linear region of the profile; first 30 min used when the profile is not linear (30% DL and above for HPMCAS; initial 30 min for PVPVA)
- used for: R18, R21, R22
- status: printed, checked against page image · recomputed: inputs not printed (slopes k not printed)
- locator: Eq. 1, p.2070; p.2074; p.2076

## 2022 Soto · E1 · surface-normalized release rate · Dissolution / A. Release mechanism and LoC

[2022-correa-soto-surfactants-clopidogrel-copovidone-asd-nanodroplets](../../../cards/2022-correa-soto-surfactants-clopidogrel-copovidone-asd-nanodroplets/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = k/(S × x)
- symbols and units: R normalized release rate (mg/min·cm²); k slope of cumulative mg released versus time (mg/min); S tablet surface area, 0.5 cm²; x fraction of the component in the ASD
- assumptions stated: exposed surface area of the eroding compact constant through the experiment; slope taken over the initial linear data points
- used for: R18
- status: printed, checked against page image · recomputed: inputs not printed (k values not tabulated; Fig. 8 gives percent release only and the linear range is not stated)
- locator: p.172

## 2022 Correasoto · E1 · surface-normalized dissolution rate · Dissolution / A. Release mechanism and LoC

[2022-correa-soto-surfactants-higher-drug-loading-atazanavir-pvpva-asds](../../../cards/2022-correa-soto-surfactants-higher-drug-loading-atazanavir-pvpva-asds/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = k/(S × x)
- symbols and units: R normalized release rate (mg/min·cm²); k slope of cumulative mg released versus time (mg/min); S tablet surface area, 0.5 cm²; x fraction of the component (ATZ or PVPVA) in the ASD
- assumptions stated: slope taken from the cumulative release profile; time window not stated
- used for: R3, R7
- status: printed, checked against page image · recomputed: inputs not printed (k slopes not reported)
- locator: p.3

## 2022 Yang · E1 · surface normalized release rate · Dissolution / A. Release mechanism and LoC

[2022-yang-release-mechanisms-rtv-pvpva-asd-phase-separation-morphology](../../../cards/2022-yang-release-mechanisms-rtv-pvpva-asd-phase-separation-morphology/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V)/(A × x)
- symbols and units: R normalized rate of release; k slope of the linear regression of total concentration versus time; V volume of dissolution medium; A exposed surface area of the compact; x weight fraction of the component of interest; units not printed
- assumptions stated: linear concentration-time regression
- used for: R1, R2 (congruency judged on normalized rates)
- status: printed, checked against page image · recomputed: inputs not printed (no k or R values reported)
- locator: pdf p.6

## 2023 Bapat · E1 · surface-area-normalized release rate (rotating disk) · Dissolution / A. Release mechanism and LoC

[2023-bapat-hpmcas-asd-media-choice-buffer-capacity-release](../../../cards/2023-bapat-hpmcas-asd-media-choice-buffer-capacity-release/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V)/(S × x)
- symbols and units: R normalized release rate (mg min⁻¹ cm⁻²); k slope of the regression line (of the release curve; units not printed); V volume of medium (100 mL); S die surface area exposed to the medium (0.5 cm²); x weight fraction of the component in the compact
- assumptions stated: only the initial linear part of each release curve used; laminar flow
- used for: R5, R7, R9, R11, R13, R18
- status: printed, checked against page image · recomputed: inputs not printed (regression slopes k)
- locator: p.5717

## 2023 Correasoto · E1 · surface-normalized release rate · Dissolution / A. Release mechanism and LoC

[2023-correa-soto-plasticizer-release-enhancement-high-tg-pvpva-asds](../../../cards/2023-correa-soto-plasticizer-release-enhancement-high-tg-pvpva-asds/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = k/(S × x)
- symbols and units: R normalized release rate (mg/min·cm²); k slope of cumulative mg released versus time; S compact surface area, 0.5 cm²; x fraction of the component in the ASD
- assumptions stated: slope from the linear region; after a lag time, from 30 to 60 min
- used for: R3, R6, R7, R12, R13
- status: printed, checked against page image · recomputed: inputs not printed (k values and release profiles not given)
- locator: p.781

## 2023 Yang · E1 · surface-normalized release rate · Dissolution / A. Release mechanism and LoC

[2023-yang-surfactant-containing-asd-release-enhancement](../../../cards/2023-yang-surfactant-containing-asd-release-enhancement/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V) / (A × x)
- symbols and units: R normalized release rate (mg min⁻¹ cm⁻², Fig. 3 axis); k slope of linear regression of total concentration vs time; V volume of dissolution medium (100 ml, P4); A exposed compact surface area (8 mm diameter die, P4); x weight fraction of the component of interest
- assumptions stated: none stated
- used for: R4, R5
- status: printed, checked against page image · recomputed: inputs not printed (k values not printed)
- locator: Eq. (1), p.2820

## 2024 Bapat · E1 · surface area and composition normalized release rate · Dissolution / A. Release mechanism and LoC

[2024-bapat-hpmcas-drug-polymer-complexation-release-performance](../../../cards/2024-bapat-hpmcas-drug-polymer-complexation-release-performance/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V)/(S × x)
- symbols and units: R normalized release rate (mg·min⁻¹·cm⁻²); k slope of the regression line (unit not stated); V volume of dissolution medium (100 mL); S die surface area exposed (0.5 cm²); x weight fraction of the component
- assumptions stated: none stated
- used for: R2-R7, R14, R15
- status: printed, checked against page image · recomputed: reproduces (25:75 LOR ASD at pH 6.8, taking k × V as drug mass released per minute: Fig. S2A ≈0.49% at 20 min and ≈2.53% at 60 min of 25 mg LOR give ≈0.0128 mg/min, R ≈0.0128/(0.5 × 0.25) ≈0.10, as in Fig. 4D and Fig. 6, not Table S3 (0.17), note X1; pH 7.5 data give ≈0.63 against ≈0.62 in Fig. 4D; plot readings)
- locator: p.1468

## 2025 Bapat · E1 · surface-area-normalized release rate · Dissolution / A. Release mechanism and LoC

[2025-bapat-hpmcas-grade-weak-base-asd-release-complexation](../../../cards/2025-bapat-hpmcas-grade-weak-base-asd-release-complexation/paper.html) · Dissolution / A. Release mechanism and LoC

- expression: R = (k × V)/(S × x)
- symbols and units: k slope of the regression line of solution concentration versus time; V volume of dissolution medium (100 mL); S die surface area exposed (0.5 cm²); x weight fraction of the component of interest
- assumptions stated: linear regression of concentration versus time over 60 min
- used for: R1, R2, R3, R4
- status: printed, checked against page image · recomputed: inputs not printed (slopes k not printed; an approximate check against Table 2 is in X8)
- locator: p.399

## 2025 Bapat · E1 · surface-area normalized release rate (intrinsic dissolution rate normalized to component weight fraction) · Peptide permeability / Peptide permeability

[2025-bapat-peptide-permeation-enhancer-pvpva-synchronous-release](../../../cards/2025-bapat-peptide-permeation-enhancer-pvpva-synchronous-release/paper.html) · Peptide permeability / Peptide permeability

- expression: R = (k × V) / (S × x)
- symbols and units: R normalized release rate (mg min⁻¹ cm⁻²); k slope of the regression line (of concentration versus time, units not stated); V volume of dissolution medium (100 mL); S die surface exposed to the medium (0.5 cm²); x weight fraction of the component
- assumptions stated: applied to the linear portion of the release curve
- used for: R2
- status: printed, checked against page image · recomputed: inputs not printed (k); reproduces within plot-reading uncertainty when k is taken from the plotted profiles: neat PVPVA ≈9 → ≈95.5% of 100 mg between 5 and 60 min (R1.b, R1.l) gives 1.57 mg/min, R = 1.57 / (0.5 × 1) = ≈3.1 versus bar ≈3.2 (R2.a); OCA in OCA:SNAC:PVPVA ≈26.5 → ≈91% of 1.6 mg between 5 and 20 min (R5.a, R5.d) gives 0.0688 mg/min, R = 0.0688 / (0.5 × 0.016) = ≈8.6 versus bar ≈8.1 (R2.f); x = 0.016 is the 1.6% DL
- locator: p.1006