Error(s) in re-building vignettes:
  ...
--- re-building ‘AUC-Calculation-with-PKNCA.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Loading required namespace: ggplot2
--- finished re-building ‘AUC-Calculation-with-PKNCA.Rmd’

--- re-building ‘Data-Cleaning-in-PKNCA.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Data-Cleaning-in-PKNCA.Rmd’

--- re-building ‘Example-theophylline.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Example-theophylline.Rmd’

--- re-building ‘Introduction-and-Usage.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Introduction-and-Usage.Rmd’

--- re-building ‘Methods-for-Dose-Aware-Interpolation-and-Extrapolation.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Methods-for-Dose-Aware-Interpolation-and-Extrapolation.Rmd’

--- re-building ‘Options-for-Controlling-PKNCA.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Options-for-Controlling-PKNCA.Rmd’

--- re-building ‘PKNCA-validation.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Quitting from lines 15-25 (PKNCA-validation.Rmd) 
Error: processing vignette 'PKNCA-validation.Rmd' failed with diagnostics:
there is no package called 'testthat'
--- failed re-building ‘PKNCA-validation.Rmd’

--- re-building ‘Selection-of-Calculation-Intervals.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Selection-of-Calculation-Intervals.Rmd’

--- re-building ‘Superposition.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Superposition.Rmd’

--- re-building ‘Writing-Parameter-Functions.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘Writing-Parameter-Functions.Rmd’

SUMMARY: processing the following file failed:
  ‘PKNCA-validation.Rmd’

Error: Vignette re-building failed.
Execution halted