How do i write a model statement for drug release kinetics

[FestusAdejoro]

I want to write a SAS syntax and run an analysis to evaluate the release of drug in an in vitro system across time periods. 

I intend to use the First order and HIguchi model equations to get values of release constant.

The equations are 

First Order: C = Coe(-kt)

Higuchi model : Mt / M∞ = Ktn (n is a superscript).

I would be grateful for any help.

Here is the syntax i was trying to develop:

DATA RELEASE;
Input TIME IVR SPECIES$;
Cards;
0.5       25.23453368 RCT

1          42.27780807 RCT

2          57.41862589 RCT

4          66.45725747 RCT

8          73.90717437 RCT

12        76.55205776 RCT

24        80.6309246 RCT

0.5       26.7912474 GCT

1          32.34728724 GCT

2          43.19154218 GCT

4          58.16394836 GCT

8          66.98968011 GCT

12        71.2555386 GCT

24        74.88005282 GCT

;

PROC SORT DATA = WORK.RELEASE;
BY SPECIES;
RUN;
PROC PLOT DATA = WORK.RELEASE;
BY SPECIES;
RUN;

[PGStats]

Use proc NLIN to fit your equations.

It is not clear what is the relationship between IVR, Mt and C.