## Wagner-Nelson, Loo-Riegelman [Dissolution / BCS / IVIVC]

Dear Dipesh!

First of all get the two ‘classical’ papers;
for the 1-compartment model,[1] and for the 2-compartment model.[2]

❝ Please suggest me the complete procedure with formula…

Below is a simple example of the Wagner-Nelson method.
1. Estimate kel from t=15 to t=32: 0.1271
2. Calculate the partial AUCs (column 3)
3. Calculate amount excreted / central volume of distribution:
column 4 = column 3 x kel
4. Calculate amount absorbed / central volume of distribution:
column 5 = column 2 + column 4
5. Calculate %absorbed:
column 6 = column 5 / asymptotic plateau (estimated as mean from t=15 to t=32: 9.976)
 ┌────┬──────┬───────┬───────┬───────┬──────┐ │ c1 │  c2  │   c3  │   c4  │   c5  │  c6  │ ├────┼──────┼───────┼───────┼───────┼──────┤ │  t │ C(t) │ AUC(t)│ Ae/Vp │ Aa/Vp │ %abs │ ├────┼──────┼───────┼───────┼───────┼──────┤ │  0 │  –   │   –   │   –   │   –   │ 0.00 │ │  1 │ 2.28 │  1.14 │  0.14 │  2.42 │ 0.24 │ │  2 │ 3.69 │  4.13 │  0.52 │  4.21 │ 0.42 │ │  3 │ 5.52 │  8.73 │  1.11 │  6.63 │ 0.66 │ │  4 │ 5.52 │ 14.25 │  1.81 │  7.33 │ 0.73 │ │  5 │ 5.08 │ 19.55 │  2.49 │  7.57 │ 0.76 │ │  6 │ 4.91 │ 24.55 │  3.12 │  8.03 │ 0.80 │ │  8 │ 4.10 │ 33.56 │  4.27 │  8.37 │ 0.84 │ │ 10 │ 3.38 │ 41.04 │  5.22 │  8.60 │ 0.86 │ │ 12 │ 3.33 │ 47.75 │  6.07 │  9.40 │ 0.94 │ │ 15 │ 2.66 │ 56.73 │  7.21 │  9.87 │ 0.99 │ │ 24 │ 0.80 │ 72.30 │  9.19 │  9.99 │ 1.00 │ │ 28 │ 0.49 │ 74.88 │  9.52 │ 10.01 │ 1.00 │ │ 32 │ 0.31 │ 76.48 │  9.72 │ 10.03 │ 1.01 │ └────┼──────┼───────┴───────┼───────┼──────┘      │0.1271│               │  9.976│      └──────┘               └───────┘

❝ … or some easily accessible reference on net.

A nice website is run by David Bourne.
If you want to examine your own data you will need the Java-plugin for your browser; for examples on absorption see this one of David's pages and followings.
1. Wagner JG, Nelson E. Per Cent Absorbed Time Plots Derived from Blood Level and / or Urinary Excretion Data. J Pharm Sci. 1965; 52: 610–1.
2. Loo JCK, Riegelman S. New Method for Calculating the Intrinsic Absorption Rate of Drugs. J Pharm Sci. 1968; 57: 918–28.

Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

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