Diapositiva 1

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SIDE BY SIDE CELL
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2 - DRUG DIFFUSION MEASUREMENT
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2 - MODELING
DONOR
RECEIVER
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DRUG CONCENTRATION INCREASE
STIRRER
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MATHEMATICALL MODELING
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SOLID SURFACE VARIATION MONODISPERSED PARTICLES
SYSTEM
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FICK LAW
1st stagnant layer
membrane
2nd stagnant layer
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BOUNDARY CONDITIONS
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BOUNDARY CONDITIONS
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BOUNDARY CONDITIONS
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SIMULATION NO DISSOLUTION
Vr Vd
H Stagnant layer thickness
hm
Dm 5.310-6 cm2/s
hm
hm
D1 8.810-6 cm2/s
hm
D1 D2
Kp 0.8
hm 100 mm
S 10 cm2
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SIMULATION PROFILE CONCENTRATION
S 10 cm2
Vr Vd
Dm 5.310-6 cm2/s
D1 8.810-6 cm2/s
D1 D2
Kp 0.8
hm 100 mm
h1 h2 0.5hm
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SIMULATION DISSOLUTION
Vd 100 cm3
Vr 800 cm3
h1 h2 hm100mm
Kp 0.8
Dm 5.310-6 cm2/s
D1 8.810-6 cm2/s
D1 D2
Kd 10-6cm/s
A 5000 g/cm2
Cs 12495 mg/cm3
S 10 cm2
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SIMULATION STEADY STATE APPROXIMATION
Cd Cd0 (constant drug concentration in the
donor) Cr 0 (sink conditions in the receiver)
FICK eq. solution (only membrane) is
Membrane Permeability
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For a trilaminate system the solution is
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SIMULATION LINEAR PROFILES (THIN MEMBRANES)
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SIMULATION LINEAR PROFILES (THIN
MEMBRANES) EMPIRICAL APPROACH
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3 - DRUG DIFFUSION COEFFICIENT MEASUREMENT
REQUIRES THE DETERMINATION OF
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CASE STUDY THEOPHYLLINE AND ALGINATES
THEOPHYLLINE MONOHYDRATED - Carlo Erba , Milano -
(C7H8N4O2H2O) MW 198, WHITE CRYSTALLINE
POWDER - DENSITY 1.49 01 g/ cm3 (Helium
picnometer) - SURFACE AREA 2941 cm2/g (mercury
porosimeter) - U.V. PEAK ABSORBANCE 271 nm
ALGINATE - Protanal LF 20/ 60, Pronova
Biopolymer, Drammen, Norway) - THEY ARE EXTRACTED
FROM BROWN SEAWEED - SEQUENCE OF GULURONATE AND
MANNURONATE (LF 20/60 70 GULURONATE) - THEY
FORM STRONG PHYSICAL GELS IN PRESENCE OF DIVALENT
IONS (TYPICALLY Ca)
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- SINK CONDITIONS - Np MONOSIZED SPHERICAL
PARTICLES (Rp0 INITIAL RADIUS)
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KDP 1.210-3 cm/s
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Cylindrical gel
V
IDR
(DISTILLED WATER 37C)
Vg
C0 20 mg/cm3
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MEMBRANE
Donor
Receiver
STAGNANT LAYER
STAGNANT LAYER
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stirrer
stirrer
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STAGNANT LAYER
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4 - RESULTS
Vd 100 cm3
Dm (5.1 0.64)10-6 cm2/s
Vr 100 cm3
S 10 cm2
P 4
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T 25C
2
4
1
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T 37C
2
4
1
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MEMBRANES CHARACTERISTICS
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DIFFUSION COEFFICIENTS