Saturated drug is encapsulated in a membrane-controlled reservoir device. the shape of the device is cylindrical. the total amount of released drug at time t can be calculated according to the following equation. m_t=(2πhdkc_s)/(ln⁡(r_0/r_i)) t the saturated drug concentration in the polymer matrix is 150 mg/cm3. the diffusion coefficient of the drug d is 2.2×10-10 cm2/s, and the partition coefficient k is 10. the length (h) and diameter (2r0) of the device are 1 cm and 500 µm respectively. the saturated drugs are in a cylindrical space with a diameter (2ri) of 200 µm. 1) calculate the amount of released drug in 48 hours. (25 points) 2) in order to apply this delivery system to children, the release rate should be reduced by 60%. how to design the device if the volume of the space for concentrated drugs and the volume of the device are both unchanged? (25 points)

1) 0.391 mg 2) By resizing the semi-permeable membrane and reducing the saturated drug concentration from 100% to 60%  (i.e. from to ).

Explanation:

1) The total amount of released drug at time 't' is:

Where:

H is the length of the device = 1 cm,

D is the diffusion coefficient of the drug

K is the partition coefficient = 10

is the saturated drug concentration in the polymer matrix

is the radius of the device = 250 μm

is the radius of the cylindrical space = 100 μm

t is the released time = 48*3600 s = 172800 s

Therefore:

2) For a membrane-controlled device, the released rate can be controlled (i.e. decrease or increase) by resizing the semi-permeable membrane. In addition, the saturated drug concentration should be reduced from 100% to 60% (i.e. from to )

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong