MATRIX-BASED CONTROLLED RELEASE DELIVERY OF ACYCLOVIR FROM POLY-(ETHYLENE CO-VINYL ACETATE) RINGS

Abstract

Up to 85% of the US adult population carries herpes simplex virus type-1 (HSV-1), with a smaller percentage (22%) infected with HSV-2. Herpesviruses can survive in lytic phase, when the viruses are actively replicating, or in latency, when the virus is functionally dormant in ganglia. Among drugs to treat these infections is acyclovir (ACV). ACV exhibits poor oral bioavailability and a short in vivo half-life; only about 10-15% of ingested drug enters the bloodstream and its half-life is about 3 hours. With those disadvantages and the possibility of poor patient compliance, viral replication may not always be suppressed. To abrogate these shortcomings we propose local distribution via sustained drug release. We present a matrix-based antiherpetic ring, composed of poly(ethylene co-vinyl acetate), that releases ACV directly to the vaginal epithelium. A 30-day in vitro drug release trial showed that approximately 135 +/- 20 μg/day of ACV was consistently released. Rings were nontoxic in cell culture and suppressed primary HSV-1 and HSV-2 replication. We expect these data form the basis for novel interventions in human health, where new prophylactics and therapeutics against genital herpes are truly needed.

Keywords: Herpes; acyclovir; controlled release; genital herpes; poly(ethylene-co-vinyl acetate); vaginal ring.

Figure 1.. Size comparison of 65% ACV (w:w) EVA25 ring to the size of an American penny.

The photo was taken using an IPhone 6S; final image was processed with Photoshop.

Figure 2.. Seven day release of ACV from devices.

Silicone (MED-4750), EVA25, and EVA40 were tested for drug release at 50% (w:w) drug load. Each device was placed in 1 mL of VFS at 37 °C. Each day for seven consecutive days, the VFS was removed and saved for HPLC analysis, then replaced with 1 mL of VFS. Each experiment was conducted in triplicate. All values are relative to day zero.

Figure 3.. Thirty days of ACV release from EVA devices.

EVA25 containing 65% ACV (w:w) or no drug, and EVA40 containing 65% ACV (w:w) or no drug, were analyzed for drug release kinetics over 30 days in VSF as in Fig 2. Each experiment was conducted in triplicate as in Fig 2. All results were quantified via HPLC and are relative to day zero.

Figure 4.. In vitro cell viability.

An MTT assay was conducted to determine the safety of EVA25 rings in vitro. Viability was measured on mock-infected cells in α-MEM alone, with EVA25 rings containing no drug, with 65% ACV (w:w) EVA25 rings, or with 50 μg/mL ACV solution added to media. Each experiment was performed four times with three replicates each (p=0.9).

Figure 5.. In vitro suppression of primary HSV infection.

In vitro infection assays were performed to analyze the suppressive capabilities of the experimental rings compared to normally infected Vero cells with no treatment. Vero cells were either mock-infected (data not shown) or infected with either (A) HSV-1 (17); (B) HSV-1 (KOS); (C) HSV-2 (MS); or (D) HSV-2 (G) in the presence of no treatment, EVA25 rings, 65% ACV (w:w) EVA25 rings, or 50 μg/mL ACV diluted in α-MEM. Titers are expressed as log (pfu/mL) for each infection/treatment combination. Experiments were performed in triplicate.