Vaginal ring adherence_in_sub-saharan_africa_expul
MICROBICIDES
1. A S E M I N A R P R E S E N T A T I O N
B Y
B E N J A M I N G O O D L U C K C .
1 2 / 1 0 3 1
M I C R O B I O L O G Y
MICROBICIDES
2. INTRODUCTION
HIV most often is spread through unprotected vaginal intercourse,
with women twice as likely as men to become infected. (UNAIDS,
2001)
Women represent more than half (52 percent) of all people living
with HIV worldwide and account for nearly 60 percent of those with
HIV in sub-Saharan Africa. (Rossi and Collins, 2014)
Efforts to promote abstinence, monogamy and the use of male
condoms have not been enough to stop the epidemic nor are these
approaches practical in many settings.
A vaginal microbicide could potentially give women the means to
protect themselves against HIV.
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3. WHAT ARE MICROBICIDES?
Microbicides are products applied inside the vagina
or rectum to protect against sexually transmitted
infections (STIs) including human
immunodeficiency virus (HIV) through sex
(Lerner, 1994)
Microbicides can be formulated as gels, creams,
films, or suppositories (Ramjee et al., 2001)
Microbicides may or may not have spermicidal
activity (contraceptive effect) (Wilkinson et al.,
2002)
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4. Fig 1. Various Microbicide products, showing;
vaginal gel, ring and film.
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5. BRIEF HISTORY
The idea for a microbicide-like product was first
proposed about 25 years ago by reproductive health
specialists and advocates who recognized the need
for female-controlled HIV prevention methods.
One of the first products considered was the
spermicide nonoxynol-9, but clinical trials found it
neither safe nor effective against HIV (Wilkinson et
al., 2002)
Trials of other so-called first generation microbicides
also yielded disappointing results.
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6. HOW DO THEY WORK?
There are different ways in which microbicides act to
prevent infection with genital pathogens.
Some microbicides (e.g Carraguard®, Cyanoviran®,
cellulose sulphate, PRO 2000®) provide a physical
barrier that keeps HIV and other pathogens from
reaching the target cells.
Another class of microbicides (e.g. Acidform®,
BufferGel®) act by enhancing the natural vaginal
defence mechanisms by maintaining an acidic pH,
which protects the vagina.
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7. Cont.
C31G and octoxynol-9 kill or disable pathogens by
stripping them of their outer covering.
Another class of products e.g tenofovir (PMPA) acts
by preventing replication of the virus after it has
entered the cell (Karim, 2010)
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9. MICROBICIDES CLINICAL TRIALS
There are three phases of clinical trials that a potential
mircobicide must pass through before it is judged effective
and safe.
1. Phase I involves a small number of volunteers to test the
safety of various doses
2. Phase II involves hundreds of volunteers to further assess
safety and, in some cases, positive responses
3. Phase III involves thousands of volunteers to test safety and
effectiveness
4. The Phase IIb trial, a recent innovation, is a larger variant of
the Phase II trial.
Phase I tends to last between twelve and eighteen months,
whereas the final phase can take up to three or four years
(Microbicides Trials Network, 2013)
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11. There are several different microbicide candidates
currently being studied. As of May 2013 there were
11 phase I trials, 1 phase I/II trial, and 4 phase III
trials. The current status of ongoing microbicide
trials can be found here (MTN, 2013)
IPM027 (The Ring Study)
MTN 020 (ASPIRE)
CAPRISA 008
FACTS 001
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12. Product Clinical Trials Country Case Study Duration
Tenofovir
Vaginal
gel
CAPRISA 004
FACTS 001
(PhaseIII)
CAPRISA 008
(PhaseIIb)
South Africa
South Africa
South Africa
889 women
2900
women
889 women
Completed
2011-2015
2011-2015
Vaginal
Rings
ASPIRE(MTN-020)
(PhaseIII)
The Ring Study
(IPM 027)
(PhaseIII)
MTN-013/IPM 026
(PhaseI)
MTN-023/IPM 30
and MTN-
024/IPM31
(PhaseI)
Malawi, Uganda,
South Africa and
Zimbabwe
South Africa and
Uganda
United States
Malawi, Uganda,
South Africa and
Zimbabwe
3476 women
1650 women
Unknown
Adolescent
girls and
post-
menopausal
women
2012-2015
2012-
2015/2016
Completed
2012-2016
Table 1: Current Microbicides Clinical Trials
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13. Which microbicide trials have recently ended?
CAPRISA 004
This phase IIb trial assessed the safety and effectiveness of
tenofovir gel in 900 HIV-negative, sexually active women
between the ages of 18 and 40 years, living in South Africa.
Results for this trial were announced in July, 2010.
The statistically significant results found:
1. Tenofovir gel reduced the risk of HIV infection by 39 percent
overall
2. Protective effect increased to 54 percent among women with
high gel adherence
The CAPRISA 004 study was the first to provide proof of
concept for microbicides. The study found statistically
significant results showing microbicides can prevent the sexual
transmission of HIV (MTN, 2011)
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14. Researchers now are evaluating microbicide
products that incorporate ARV drugs, including
ARVs commonly used in HIV treatment.
The most studied ARV-based microbicide is
tenofovir gel, which was found safe and effective in
reducing HIV risk in women who used it before and
after vaginal sex in a study called CAPRISA 004 but
not effective in another study known as VOICE,
which was designed to evaluate its daily use (as well
as daily use of either the oral ARV tablet tenofovir or
Truvada).
TENOFOVIR/VAGINAL GELS
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16. Fig.5: Picture showing the oral ARV
tablet and the tenovovir vaginal gel
L-R:
Left: Oral ARV tablet
(tenofovir)
Right: Tenofovir Vaginal
gel
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17. As an alternative to vaginal gels, researchers are
evaluating other formulations, including paper-thin
quickdissolve vaginal films that after insertion would
melt away and disperse active drug to protect cells in
the vagina.
Films are in the early phases of clinical testing.
VAGINAL FILMS
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19. VAGINAL RINGS
Vaginal rings, flexible products that fit comfortably
inside the vagina and provide sustained delivery of
drugs over a period of time, are being tested in both
early phase studies and Phase III trials.
Vaginal ring products are already used in many
countries to deliver hormonal contraception.
For HIV prevention, the dapivirine ring is the first
vaginal ring – and the first HIV-prevention product
intended for monthly use – to enter efficacy testing.
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20. Cont.
Vaginal rings containing both an ARV
and a contraceptive are also being
developed that would potentially
provide women both HIV protection
and contraception in a single product.
Phase I trials began in 2014.
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22. RECTAL MICROBICIDES
Although the majority of microbicide research has
focused on products to prevent HIV through vaginal
sex, anal sex is common among men who have sex
with men (MSM) and practiced by women around
the world.
According to some estimates, the risk of infection
through anal sex is 20 times greater than vaginal sex
because the rectal lining, the mucosa, is thinner and
much more fragile than the lining of the vagina.
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23. CONT.
An important first step to the development of rectal
microbicides has been evaluating the rectal safety of
microbicides originally formulated as vaginal gels, in
particular, tenofovir gel.
An early study found that the vaginal formulation of
tenofovir gel caused gastrointestinal side effects when
used in the rectum, so researchers tested a reformulated
version of the gel with less glycerin in a follow-up study
called MTN-007.
That study found the reduced glycerin gel safe,
acceptable and better tolerated than the vaginal gel when
used in the rectum.
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24. HOW IS IT FUNDED?
In 2011 around $186 million was invested in microbicide
research and development (a 25 percent decrease on the
previous year).
This decline has been associated with the cycle of funding
disbursement, rather than a decline in investment.
About 95 percent of this money came from the public sector, 5
percent came from the philanthropic sector, and <1 percent
was accounted for by commercial companies (only $1 million).
To ensure microbicides a
re available to women in low- and middle-income countries,
profit margins would need to be low (UNAIDS, 2008)
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25. CONCLUSION
A safe and effective microbicide has potential to
become a key method of HIV prevention. As the
trials above demonstrate, microbicide research and
development brings us ever closer to having a
successful candidate.
Any successful product would have to undergo
review and licensing by regulatory agencies before
becoming available to the public.
It would take time to work out the best formulation
and dosage; find a suitable delivery method; and
distribute the product.
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26. REFERENCES
HIV Vaccines and Microbicides Resource Tracking Working Group
(2012) Investing to End the AIDS Epidemic: A New Era for HIV
Prevention Research & Development
Karim, Q.A. (2010) ' Effectiveness and safety of tenofovir gel, an
antiretroviral microbicide, for the prevention of HIV infection in
women', Science 329(5996)
Lerner S., (1994). Microbicides: a woman-controlled HIV
prevention method in the making. SIECUS : 22:10-3.
Lisa Rossi and Clare Collins. 2014. “ Fact sheet about microbicides”.
Microbicides Trials Network, www.mtnstopshiv.org
Microbicide Trials Network, (2011). MTN Statement on Decision to
Discontinue Use of Tenofovir Gel in VOICE, a Major HIV
Prevention Study in Women
Microbicide Trials Network, (2013). Fact Sheet: Understanding the
results of VOICE
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27. Cont.
UNAIDS, (1996). International Working Group on Vaginal Microbicides,
Recommendations for the development of microbicides. AIDS, 10:1-6.
Ramjee G, Gouws E, Andrews A, Myer L, Weber A.E., (2001). The
acceptability of a vaginal microbicides among South African men.
International Family planning Perspectives, 27:164-170.
UNAIDS, (2001). AIDS epidemic update: Joint United Nations Programme
on HIV/AIDS and the World Health Organization.
UNAIDS, (2008). Microbicides: challenges to development and
distribution.
Wilkinson D, Tholandi M, Ramjee G, Rutherford GW., (2002). Nonoxynol-
9 spermicide for prevention of vaginally acquired HIV and other sexually
transmitted infections: systematic review and meta-analysis of randomised
controlled trials including more than 5000 women. Lancet Infectious
Diseases; 2:613-617
World Health Organization, (2009). Regulatory issues in microbicide
development.
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