There are different types of microbicides being tested. An analogy is
the detergent. Detergents are meant for laundry, yet there are
differnt types: omo, surf, klin, elephant etc. So is it with
microbicides. There are different microbicides with different names
and different modes of actions.

Below, we would quickly go through what the types of microbicides are
and how they work
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Curently there are five groups of Microbicides

1. Detergents also known Surfactants

2. PH modifier also known as body enhancer

3. Polyanions also known as fusion/entry inhibitors

4. ARV based microbicides

5. Unknown mechanisms
1. Examples of detergents
a. Nonoxynol-9 (N9): a detergent present in spermicides and some
vaginal lubricants. Regular and frequent use of the product destroys
the vaginal epithelium

b. SAVVY: Though a surfactant, was found safe but not effective
in preventing HIV infection due to the low HIV incidence in the
regions of study for efficacy to be established
2. Polyanions
a.CS3 also called Ushercell. Found associated with an increased
rate of infection at some of the clinical sites through unknown
mechanisms.

b. Pro 2000 which is a ulphonated polymer. Its inhibits the
attachment of the virus to cells. They are charged polymers. Studies
being conducted by MDP and HPTN use these products. Concentrations of
0.5% is currently being studied in 2 trials

c. Carraguard: Contains Carrageanan which is a product from
seaweed. It binds to the body cells or disease causing organisim
before they can invade and attach. Studies show the product is safe
but not effective in preventing HIV infection. If also does not
prevent pregnancy

3. PH modifier or body defence enhancer
a. Buffer gel: This is a broad spectrum microbicide. Buffer gel
works by keeping the vagina at a low pH (the normal PH) during and
after sex. HIV prefers a basic environment that is, an environment
with a high pH. Studies have shown that HIV is inactivated at a PH
below 4 to 5.8. Buffer gel thus works by boosting the natural body
defence mechanism: increases lactobacilli or rapidly acidifies the
ejaculate

4. ARV Based Microbicide
This group of microbicide are currently being studied. They ARV based
microbicide would not be able to prevent the vagina cells from being
infected BUT should prevent HIV from replicating within the infected
cells. There are a lot of current studies going on at preclinical and
clinical phases. As you follow Microbicide research, you would read
and hear about PMPA (tenofovir based microbicide), UC-781, TMC 120
and MIV 150.

5. Unknown action
Currently, India is studying a herbal preparation for use as
microbicide called Praneem. Its possible mechanism of action is not
known.