LNG pharmacokinetics in a rabbit model.

<p>Pharmacokinetic (PK) testing of end-capped 10 or 20 mm PEU-1/PEU-2 LNG segments in New Zealand white rabbits. (A) Parallel <i>in vitro</i> release data for the same LNG segment lot used in the study and (B) comparison with <i>in vivo</i> data for the 28 and 90 day study groups. A subtraction of the mean LNG recovery between study groups was performed to directly compare <i>in vitro</i> and <i>in vivo</i> behavior from day 28 to day 90. (C) Plasma LNG levels measured during the rabbit PK study for 10 and 20 mm LNG segment implantations. (D) Individual and median (bar) LNG levels determined from extractions of cervical tissue. Some samples in the 10 mm study groups were below quantification (BLOQ: <0.750 ng LNG per g tissue). BLOQ data points are graphed as LOQ/2 (0.375 ng/g). <i>In vitro</i> data represents N = 5, mean ± SD and <i>in vivo</i> data represents N = 6, mean ± SD (except for the <i>in vivo</i> “difference” data points, which are subtractions of mean values).</p

Model for dissolved drug release from cylindrical reservoirs.

<p>(A) Accuracy of the two stage drug release model (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e012" target="_blank">Eqn. 11</a>) for LNG segments stored 76 days at 40°C to completely equilibrate LNG loading throughout the cross-section. Experimental data represent N = 3, mean ± SD. Effects of (B) EG-65D RCM thickness (in µm) and (C) diffusivity (in cm²/s) on the reservoir-stage model (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e012" target="_blank">Eqn. 11b</a>) for 20 mm length segments with 5.5 mm diameter. Effects of (D) PEU-2 RCM thickness, and (E) diffusivity on the burst duration (<i>t_b</i>) predicted by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e006" target="_blank">Equation 6</a>. For panels C and E RCM thickness was fixed at 100 µm. (F) Maximal burst amount (<i>M_b</i>) shown as a function of RCM thickness.</p

<i>In vitro</i> release of TFV and LNG from full two-segment IVR.

<p><i>In vitro</i> release of (A) TFV and (B) LNG for 90 days from final TFV/LNG (20 mm) IVR prototypes using Tecophilic and Tecoflex polymers (HP-100A-60 TFV reservoir tube, EG-85A LNG reservoir core and EG-65D LNG reservoir RCM and end-caps). LNG reservoir RCM thicknesses were measured between 74 and 85 µm. All data represent N = 5, mean ± SD.</p

Measured LNG effective diffusivities for various PEUs, calculated using Equation 12. Data represents N between 3 and 8, mean ± SD.

<p>Measured LNG effective diffusivities for various PEUs, calculated using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e013" target="_blank">Equation 12</a>. Data represents N between 3 and 8, mean ± SD.</p

<i>In vitro</i> release of LNG from reservoir segments.

<p>(A) Effect of partial LNG loadings in the RCM on lag/burst behavior in LNG <i>in vitro</i> release kinetics for 10 mm length PEU-1/PEU-2 segments, achieved by 40°C storage for varying duration. <i>In vitro</i> LNG release from 20 mm length, 5.5 mm diameter co-axially extruded EG-85A segments with (B) EG-65D or (C) EG-60D RCMs of various thicknesses. (D) Full 90 day <i>in vitro</i> release kinetics from the 84 µm EG-65D RCM group with model comparison (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e012" target="_blank">Eqn. 11</a>). All data represent N = 5, mean ± SD except panel A (N = 3). Segments in panels B–D were all stored for 14 days at 40°C before testing.</p

Determination of LNG effective diffusivities in PEU.

<p>(A) Example square-root-of-time fitting for PEU-1 and PEU-2 used to estimate LNG-PEU diffusivity values (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088509#pone.0088509.e013" target="_blank">Eqn. 12</a>). (B) Log-log correlation between LNG diffusivity and reported flexural modulus for Tecoflex PEUs and (C) effect of temperature on LNG diffusivity in PEU-1 and PEU-2.</p

Engineering a Segmented Dual-Reservoir Polyurethane Intravaginal Ring for Simultaneous Prevention of HIV Transmission and Unwanted Pregnancy

<div><p>The HIV/AIDS pandemic and its impact on women prompt the investigation of prevention strategies to interrupt sexual transmission of HIV. Long-acting drug delivery systems that simultaneously protect womenfrom sexual transmission of HIV and unwanted pregnancy could be important tools in combating the pandemic. We describe the design, <i>in silico</i>, <i>in vitro</i> and <i>in vivo</i> evaluation of a dual-reservoir intravaginal ring that delivers the HIV-1 reverse transcriptase inhibitor tenofovir and the contraceptive levonorgestrel for 90 days. Two polyether urethanes with two different hard segment volume fractions were used to make coaxial extruded reservoir segments with a 100 µm thick rate controlling membrane and a diameter of 5.5 mm that contain 1.3 wt% levonorgestrel. A new mechanistic diffusion model accurately described the levonorgestrel burst release in early time points and pseudo-steady state behavior at later time points. As previously described, tenofovir was formulated as a glycerol paste and filled into a hydrophilic polyurethane, hollow tube reservoir that was melt-sealed by induction welding. These tenofovir-eluting segments and 2 cm long coaxially extruded levonorgestrel eluting segments were joined by induction welding to form rings that released an average of 7.5 mg tenofovir and 21 µg levonorgestrel per day <i>in vitro</i> for 90 days. Levonorgestrel segments placed intravaginally in rabbits resulted in sustained, dose-dependent levels of levonorgestrel in plasma and cervical tissue for 90 days. Polyurethane caps placed between segments successfully prevented diffusion of levonorgestrel into the tenofovir-releasing segment during storage.Hydrated rings endured between 152 N and 354 N tensile load before failure during uniaxial extension testing. In summary, this system represents a significant advance in vaginal drug delivery technology, and is the first in a new class of long-acting multipurpose prevention drug delivery systems.</p></div

IVR Design Overview.

<p>Structural formulae of (A) the HIV-1 nucleotide reverse transcriptase inhibitor tenofovir (TFV) and (B) the progestin contraceptive levonorgestrel (LNG). (C) A design schematic of the full TFV/LNG IVR, shown in the 20 mm LNG segment configuration illustrating the LNG-loaded core (green), the rate-controlling membrane (RCM, red), diffusion-limiting end-caps (blue) and the hollow HPEU tube containing TFV-loaded paste (gray). (D) Photographs of TFV/LNG IVR in the 10 mm (left) and 20 mm (right) LNG segment configurations. (E) Illustration of a reservoir cross-section with outer and inner radii <i>r_o</i> and <i>r_i</i>, and core drug concentration <i>c_in</i>. (F) Photomicrograph of the LNG segment cross-section showing microscopic measurement of RCM thickness. (G) Component parts of the TFV/LNG IVR: a TFV paste-filled HPEU tube (bottom), a co-axially extruded LNG-loaded reservoir segment (top) and two diffusion-limiting end-caps (left and right).</p

Variations in participant folding/squeezing techniques for IVR insertion.

<p><u>Panel A</u>: standard squeezing of IVR involving squeezing the ring between the thumb and middle finger and using the index finger to guide, then push the ring further into the vagina. <u>Panel B</u>: squeezing of IVR using both the index and middle finger on one side and the thumb on the opposite side, for initial insertion; then using fingers to push the ring into place in the vagina. <u>Panel C</u>: the “figure-8” folding method involving squeezing the ring in the middle, twisting it at the center to make a figure-8, then folding it over, and holding the ends together for insertion.</p

Increases in Endogenous or Exogenous Progestins Promote Virus-Target Cell Interactions within the Non-human Primate Female Reproductive Tract

<div><p>Currently, there are mounting data suggesting that HIV-1 acquisition in women can be affected by the use of certain hormonal contraceptives. However, in non-human primate models, endogenous or exogenous progestin-dominant states are shown to increase acquisition. To gain mechanistic insights into this increased acquisition, we studied how mucosal barrier function and CD4+ T-cell and CD68+ macrophage density and localization changed in the presence of natural progestins or after injection with high-dose DMPA. The presence of natural or injected progestins increased virus penetration of the columnar epithelium and the infiltration of susceptible cells into a thinned squamous epithelium of the vaginal vault, increasing the likelihood of potential virus interactions with target cells. These data suggest that increasing either endogenous or exogenous progestin can alter female reproductive tract barrier properties and provide plausible mechanisms for increased HIV-1 acquisition risk in the presence of increased progestin levels.</p></div