Amphora™ (ACIDFORM)

Amphora™, clinically developed under the name ACIDFORM, is a vaginally-applied gel or tablet designed to protect women against becoming pregnant and contracting Sexually Transmitted Infections (STI) during intercourse. It has also shown efficacy as a preventative against vaginal infection, include Bacterial Vaginosis (BV), when used preemptively. It remains effective when applied 8-10 hours before intercourse.

Most promising about Amphora™ is its potential as a delivery platform for other drugs and microbicides, boosting their efficacy and allowing them to remain in place and effective for hours rather than minutes.

Click here for a detailed review of all clinical work performed to date on Amphora™

• The Technology
• The Platform
• The Results

The Technology
Amphora™ works by two primary mechanisms of action:

Vaginal pH Buffer
Amphora™ enhances the natural defenses of the vagina by maintaining its normal acidic pH, despite the introduction of semen, an alkaline substance, during intercourse. With Amphora™, the vaginal environment is sustained at its normal acidic pH which has been shown to be naturally hostile to sperm and microbes that cause STI.

Bio-Adhesive Barrier
Amphora™ forms a protective physical barrier over the cervix and vaginal walls, entrapping and prevent sperm and microbes from penetrating the vaginal wall and cervix by creating a protective, long-lasting coating over the vaginal surface.

The Platform

The most promising attribute of Amphora™ is its potential as a delivery platform for other drugs and microbicide agents. With the recent marginal success of PRO-2000 in combating HIV infection, the industry's focus is shifting towards combination products with multiple mechanisms of action. Amphora™ is the only agent capable of delivering these other microbicides while boosting efficacy as well as retaining them in the vagina for hours, allowing them to protect for a much greater period of time.

Amphora™ can be detected in the vagina 24 hours after application. It was shown to be effective in buffering and preventing sperm entry into cervical mucus when placed vaginally 8-10 hours before intercourse. Amphora™ produces a physical layer of gel (“film”) over the vaginal and cervical surfaces. This layer remains for at least 12 hours and is difficult or impossible to remove by flushing the vagina with saline.

In an HSV study in mice performed at Mt Sinai School of Medicine, both Amphora™ and PRO-2000 were effective in preventing the spread of HSV, however the effects of PRO-2000 when delivered in an acid-buffering agent such as Amphora™ at pH 4.5, the results were additive.

Amphora™ is being evaluated as the ideal delivery vehicle for other microbicides in development to broaden the scope of protection, increase efficacy and prolong the protective benefits.

The Results

Safety
Amphora™ has been cleared by the FDA as safe for use in humans. It received 510(k) device clearance as a lubricant in 2004 and is currently the only microbicide candidate to date able to be marketed and sold for human use.

510(k) Approval Press Release (2004)
Properties of a new bioadhesive vaginal formulation (ACIDFORM)
Study of the Vaginal Tolerance of ACIDFORM
Male Tolerance of ACIDFORM Gel

Contraceptive
Amphora™ has shown to be an effective spermicide even when applied 8-10 hours before intercourse in a Phase II/IIb post-coital study. The study compared the gel to the currently marketed spermicide, Nonoxynol-9 (N-9), and found Amphora™ to be as effective or more effective than N-9.

Phase II/IIb Contraceptive Study: Amphora™ - Nonoxynol-9

STI Prevention
HIV
Amphora™ has demonstrated potent and broad anti-HIV potential in several in-vitro and animal clinical studies.

A number of articles have reported the inactivation of HIV at the acidic pH of the vagina (Martin et al, 1985; Ongradi et al, 1990; Kempf et al, 1991; Voeller and Anderson, 1992; O’Connor et al, 1995; Bos et al, 1998). When Amphora™ is preincubated with virus (strain IIIB) for 5 minutes, the mixture neutralized (to pH 7.2), and incubated with host cells, HIV inhibition is obtained with an EC50 at an 82 fold ACIDFORM dilution (Doncel, unpublished). When Amphora™ was diluted in medium and mixed for two minutes with virus (HIV-1 RF strain) and subsequently added to target cells, a 1:8 dilution displayed virucidal activity. In another study by the same investigator, Amphora™ was tested in the presence of proteins. After a 2 hour compound/virus/cell incubation, Amphora™ displayed antiviral activity against the cell-free X4 HIV-1 strain with an IC50 at 1:140 dilution of Amphora™. Another laboratory found that both the UR5 and X4 types of HIV are susceptible to Amphora™ (Herold, unpublished). HIV can be spread sexually as a cell-free and as cell-associated virus. Mild acidity inactivates leukocytes (monocytes, macrophages and lymphocytes; host cells for HIV), completely abolishing progressive motility at a pH between 5.5 and 6.0 (Olmsted et al, 2002).

HSV (Herpes)
Amphora™ inhibits the herpes virus 2 (HSV-2) in vitro (Herold, unpublished). In one study, the HSV titer was reduced by more than 90% following exposure to pH 4.5; time studies indicated that HSV infection is reduced 90% after a 2 minute exposure to acidic pH and 99% after 30 minutes (Tuyama, Li, Carlucci, Cheshenko, Goldberg, Keller and Herold, unpublished).

Amphora™ appears to be truly virucidal and has a broad spectrum inactivating effect. In the mouse model, Amphora™ is as effective as marketed nonoxynol-9 products (Gynol II, K-Y plus, Advantage S and Conceptrol) in providing prophylaxis against herpes infection, producing a protection rate of about 30-50% (Bourne et al, 1999; Bourne et al, unpublished). Others found that pretreatment of mice, 15 minutes before vaginal challenge with a clinical isolate of HSV-2, resulted in an 80% infection rate in vehicle control-treated animals and a 30% infection rate in Amphora™-treated animals (Tuyama, Li, Carlucci, Cheshenko, Goldberg, Keller and Herold, JID 2006:194).

Amphora™ Inactivates Herpes Simplex Virus and Prevents Genital Herpes in a Mouse Model

Gonorrhea
Amphora™ inhibits the growth of gonococci completely in vitro (Spencer et al, 2002, 2003). At dilutions of 2% and above, all 7 gonococcal strains tested are inhibited. Even at 0.625%, 6/7 strains are inactivated. In the mouse model, vaginally placed Amphora™ is also very effective in preventing the transmission of gonococci. Infectivity was reduced from 87% in the control to 6% in the Amphora™-treated animals (Spencer et al, 2002, 2003).

Inhibition of Neisseria gonorrhoeae Genital Tract Infection

Chlamydia
Amphora™ is more effective than marketed nonoxynol-9 containing products in providing protection against chlamydia infection in the mouse model (Pilipenko et al, 1999; Bourne et al, unpublished). Amphora™ provided protection against upper genital tract infection in 88-100% of the animals, whereas Gynol II, K-Y plus, Advantage S and Conceptrol provided protection to only 0 - 38% of the animals.

Bacterial Vaginosis (BV) and Vaginitis
Acid conditions such as those found in the vagina were reported to inhibit the growth of Gardnerella and various BV-associated organisms (no or very little growth at pH 5.5 or below; Nagy et al, 1991).

In vitro studies Amphora¡ inhibits many vaginitis- and BV-causing microbes (Tevi-Bennison et al, 2002; Citron, unpublished). The following microbes survived for one hour or less, and can be considered very susceptible to Amphora:

The following microbes survived between 1 and 7 hours under these conditions, and are moderately susceptible to Amphora™:

Using the Microbial Challenge Test, in which microbes are directly injected into Amphora™, samples collected after 14 and 28 days, and cultured, no microbes were recovered at either time point (unpublished). The following organisms were tested: 1. Aspergillus niger 2. Candida albicans 3. Staphylococcus aureus 4. Escherichia coli 5. Pseudomonas aeruginosa Trichomonas vaginalis was also effectively inhibited by Amphora™ (Tevi-Bennison et al, 2002).

For the qualitative assay, a suspension of 10,000 parasites was added to different dilutions of ACIDFORM and incubated for 48 hours. One set was incubated under aerobic conditions and the other under anaerobic conditions. The incubates were subsequently examined for moving trichomonads (a single moving trichomonad was considered a test failure). For quantitative evaluation, thymidine uptake studies were performed to test trichomonad survival. In the qualitative study, Amphora™ was toxic to trichomonads under aerobic conditions at 1:30 dilution, and under anaerobic conditions at a 1:18 dilution. In the quantitative study, Amphora™ was inhibitory under aerobic conditions at dilutions ranging from 1:50 to 1:100, and under anaerobic conditions at 1:18 to 1:30 dilutions.