## Get Fabs if no iv data... [Dissolution / BCS / IVIVC]

Hi Thalita,

If you do not have iv data for your subjects and you still want to get Fabs (fraction cumulative absorption in %) and then do Levy plots, I think probably you can do the following:

» ... I just tried to calculate Fabs based on Wagner Nelson equation, but the values of Fabs were higher than 1. The Kel is too little. On my work group we have a study that used same in vivo data with GastroPlus and establish the correlation based on one-compartment model, because we do not have intravenous data.

R codes

If you do not have iv data for your subjects and you still want to get Fabs (fraction cumulative absorption in %) and then do Levy plots, I think probably you can do the following:

- fit your data with one-compartment PK model, to get Ka, Kel & Vd;

- use obtained 'Kel' to calculate Fabs (R codes as follows);

- plot Fabs vs. FRD (from your dissolution profiles, varied pH) and get Levy plots.

» ... I just tried to calculate Fabs based on Wagner Nelson equation, but the values of Fabs were higher than 1. The Kel is too little. On my work group we have a study that used same in vivo data with GastroPlus and establish the correlation based on one-compartment model, because we do not have intravenous data.

R codes

`for (j in 1:length(W.split)){ ### 'W.split' contains in-vivo data for all subj., j = # of subj.`

auc<- 0;Ft<- 0;Fabs<- 0

for(i in 2:length(W.split[[j]][["time"]])){

# calculate AUC for each time point

auc[i]<- (W.split[[j]][["time"]][i]-W.split[[j]][["time"]][i-1])*(W.split[[j]][["conc.obs"]][i]+W.split[[j]][["conc.obs"]][i-1])* 0.5

auc[i]<- auc[i]+auc[i-1]

# calculate F(t): fraction of absorption at time t

Ft[i]<-W.split[[j]][["conc.obs"]][i]+kel*auc[i]}

# calculate AUC (0~INF)

auc.infinity<-W.split[[j]][["conc.obs"]][length(W.split[[j]][["conc.obs"]])]/kel

aucINF<-auc[length(W.split[[j]][["conc.obs"]])]+auc.infinity

# calculate Fabs(t): cumulative absorption fractions at time t

Fabs<- 0

for(i in 2:length(W.split[[j]][["time"]])) Fabs[i]<-(Ft[i]/(kel*aucINF))*100

—

All the best,

-- Yung-jin Lee

Kaohsiung, Taiwan http://pkpd.kmu.edu.tw/bear

Download link (updated) -> here

All the best,

-- Yung-jin Lee

**bear****v2.8.6**:- created by Hsin-ya Lee & Yung-jin LeeKaohsiung, Taiwan http://pkpd.kmu.edu.tw/bear

Download link (updated) -> here

### Complete thread:

- IVIVC with Bioequivalence Data thalita_m 2019-06-18 01:55 [Dissolution / BCS / IVIVC]
- IVIVC or not IVIVC? yjlee168 2019-06-18 20:57
- IVIVC or not IVIVC? thalita_m 2019-06-20 22:40

- Get Fabs if no iv data... yjlee168 2019-06-19 09:36

- IVIVC or not IVIVC? yjlee168 2019-06-18 20:57