The Viadur® leuprolide acetate implant was developed by Alza (now part of Johnson & Johnson) and marketed by Bayer until it was discontinued in 2007 due to generic competition. Viadur® gained FDA approval in 2000 for the treatment of prostate cancer and utilized the DUROS® platform. The DUROS®titanium implant is 4 mm in diameter by 45 mm in length and provides osmotically driven, zero-order drug delivery (
Fig. 9) [
71,
72]. The implant is placed under the skin on the inside of the upper arm with the aid of a trocar. At the end of the one year delivery duration, the empty system is explanted. Viadur® delivered leuprolide (370 mg/ml leuprolide in dimethyl sulfoxide) continuously over 1 year at ~120 μg/day (0.4 μl/day) from a 150 μl drug reservoir [
73].
In vitro and
in vivo (rats and beagles) release rate data demonstrated zero-order delivery for 1 year [
72,
74]. Serum testosterone and leuprolide levels were also monitored and showed steady release rates for 12 months.
Fig. 9
Diagram of a DUROS® osmotic implant. Reproduced with permission from Fig. 1 in [
72] (©2001 Elsevier).
Durect Corp. licensed the DUROS® platform from Alza for pain indications. The CHRONOGESIC®reservoir contained ~155 μl sufentanil in benzyl alcohol and provided zero-order release at 5 μg/hr [
75]. Durect initiated Phase 3 trials with sufentanil for moderate to severe chronic pain. However, the trial was suspended in 2003 due to premature shutdown of devices [
76].
Intarcia Therapeutics uses the DUROS® implant for the delivery of exenatide (type 2 diabetes) and ω-interferon (Hepatitis C) [
77]. Exenatide was formulated for a 6 month (45 μg/day), 9 month (30 μg/day), and 12 month (10 μg/day) duration and showed good stability at 25°C and 37°C for 12 months [
78]. Furthermore, exenatide was dosed at 20-80 μg/day for 6 months in Phase 2b trials [
79]. Intarcia also has ω-interferon in Phase 1b (25 μg/day and 50 μg/day) for Hepatitis C [
80,
81]. ω-interferon was formulated as a suspension and showed good stability for 2 years at 30°C. The protein was delivered from the device at 9 μg/day and 22 μg/day for 6 months at 37°C.
Adv Drug Deliv Rev. 2012 Nov; 64(14): 1590–1602.
Published online 2012 Feb 21. doi:
10.1016/j.addr.2012.02.005
PMCID: PMC3430809
NIHMSID: NIHMS360102
Reservoir-Based Drug Delivery Systems Utilizing Microtechnology
Cynthia L. Stevenson,a
John T. Santini, Jr.,a,* and
Robert Langerb