pkpd.Release (version 0.1.0)

korsmeyer_peppas_model: Korsmeyer-Peppas Drug Release Kinetic Model

Description

Fits experimental cumulative drug release data to the Korsmeyer-Peppas model using log10-transformed fraction released vs. log10-transformed time. The function automatically normalizes cumulative percent drug release to fraction (0-1) by default and removes t = 0. In addition, the function supports optional grouping variables (e.g., formulation, batch) and optional pH-dependent analysis. It generates publication-quality plots with experimental curves, fitted Korsmeyer-Peppas straight lines, mechanism table, and annotations for Korsmeyer-Peppas release constant (kKP), release exponent (n), intercept, coefficient of determination (R^2), and the time required for 50-percent drug release (t50).

Users can toggle 'normalize = TRUE/FALSE' to use fraction (0-1) or raw percent drug release.

Model: log10(Mt/MInf) = log10(k) + n * log10(t)

The release exponent, n, indicates the drug release mechanism: - n = 0.5 : Fickian diffusion - 0.5 < n < 1 : Non-Fickian (anomalous) diffusion - n = 1 : Case II transport (zero-order release) - n > 1 : Super Case II transport

Value

A list containing:

fitted_parameters

Data frame with kKP, n, intercept, R^2, and t50 for each group.

data

Processed data used for fitting and plotting.

Arguments

data

A data frame containing experimental cumulative percent drug release.

time_col

Character string specifying the column name for time (minutes).

release_col

Character string specifying the column name for cumulative percent drug release.

group_col

Optional character string specifying a grouping variable (e.g., formulation, batch).

pH_col

Optional character string specifying a column containing pH values.

plot

Logical; if TRUE, generates a plot with fitted Korsmeyer-Peppas lines.

annotate

Logical; if TRUE, annotates the plot with kKP, n, intercept, R^2, and t50 (only if <= 2 groups).

normalize

Logical; if TRUE (default), normalizes cumulative percent release to fraction (0-1). If FALSE, retains original percent values.

Author

Paul Angelo C. Manlapaz

References

Korsmeyer, R. W., Gurny, R., Doelker, E., Buri, P., & Peppas, N. A. (1983) <doi:10.1016/0378-5173(83)90064-9> Mechanisms of solute release from porous hydrophilic polymers. International Journal of Pharmaceutics, 15(1), 25–35.

Examples

# Example I: Single formulation
df1 <- data.frame(
  time = c(0, 15, 30, 45, 60, 90, 120, 150, 180),
  release = c(0, 11.4, 20.8, 30.8, 39.8, 57.8, 72, 84.8, 93.5)
)
korsmeyer_peppas_model(
  data = df1,
  time_col = "time",
  release_col = "release",
  normalize = TRUE  # default
)

# Example II: Two formulations (grouped, not pH-dependent)
df2 <- data.frame(
  time = rep(c(0, 30, 60, 90, 120, 150), 2),
  release = c(
    0, 18, 35, 55, 72, 88,  # Formulation A
    0, 12, 26, 40, 58, 70   # Formulation B
  ),
  formulation = rep(c("Formulation A", "Formulation B"), each = 6)
)
korsmeyer_peppas_model(
  data = df2,
  time_col = "time",
  release_col = "release",
  group_col = "formulation"
)

# Example III: pH-dependent release
df_pH <- data.frame(
  time = rep(c(0, 60, 120, 180), 2),
  release = c(0, 40, 75, 95, 0, 30, 60, 80),
  pH = rep(c(7.4, 4.5), each = 4)
)
korsmeyer_peppas_model(
  data = df_pH,
  time_col = "time",
  release_col = "release",
  pH_col = "pH"
)

# Example IV: Two formulations under two pH conditions
df1 <- data.frame(
  time = rep(c(0, 20, 40, 60, 80, 100, 120, 140, 160, 180), 2),
  release = c(
    0, 12, 25, 38, 50, 62, 73, 82, 89, 95,  # pH 4.5
    0, 15, 30, 45, 59, 70, 79, 86, 91, 97   # pH 7.6
  ),
  pH = rep(c(4.5, 7.6), each = 10)
)
df2 <- data.frame(
  time = rep(c(0, 15, 30, 45, 60, 75, 90, 105, 120, 135), 2),
  release = c(
    0, 10, 22, 34, 46, 57, 67, 76, 84, 91,  # pH 4.5
    0, 13, 27, 41, 55, 67, 77, 85, 92, 98   # pH 7.6
  ),
  pH = rep(c(4.5, 7.6), each = 10)
)
df_all <- rbind(
  cbind(formulation = "Dataset 1", df1),
  cbind(formulation = "Dataset 2", df2)
)
korsmeyer_peppas_model(
  data = df_all,
  time_col = "time",
  release_col = "release",
  group_col = "formulation",
  pH_col = "pH"
)