New Frontiers in Contraceptive Research A Blueprint for Action (2004) / Chapter Skim
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Appendix A: Examples of Progress and Impediments in Contraceptive Research and Development
Appendix A: Examples of Progress and Impediments in Contraceptive Research and Development
Pages 163-201
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From page 163... ...
Several microbicides are already in clinical trials to test their efficacy in preventing pregnancy and STI transmission, but many others are also at earlier stages of development. Examples of microbicides in development are listed in Table A.2.
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From page 164... ...
Progesterone Hormone/ Over 98.5% Inhibits cervical mucus Approver vaginal ring vaginal ring. when used production and prevents as directed.
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From page 165... ...
Minimal. Same as those for combination oral hormonal contraceptives.
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Seasonale Hormonal oral Over99% Used for 84 days before a 7-day Develope contraceptive when used placebo instead of the usual Received as directed. 21-day/7-day cycle.
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From page 167... ...
Developed by Population Council. Received FDA approval in 1996; presently approved for use for up to 5 years.
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From page 168... ...
LNG Hormonal oral Reduces the Believed to act as an EC FDA app (Levonorgestrel) contraceptive risk of principally by preventing following Known as Plan B pregnancy ovulation or fertilization; it may the only ~ when used for from ~ 8% also inhibit implantation, but is Develope emergency to 1.1% not effective once implantation (WCC)
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Developed by Organon, Inc. Received FDA approval in May 2003.
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. Today Sponge Vaginal barrier 89% to 91% The active ingredient in the FDA app when used Today Sponge is nonoxynol-9.
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From page 171... ...
and FHI. cap in FemCap, Inc., received FDA approval on Minimal.
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Prevents follicular growth and suppresses ovulation. NA NA Female hormonal Phase II trials contraceptive, indicate over progestin and 90% ovulation estrogen.
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Developed by the Population Council. Phase II trials completed, phase III trials formulation and manufacture by Q Pharma in Sweden.
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Insertion procedure does not require an incision in the abdominal cavity and can be performed under local anesthesia. Chemical Nonsurgical NA scarring sterilization Two different chemical combinations can be used to achieve scarring that eventually blocks the fallopian tubes: phenol (carbolic acid)
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Received FDA approval in September 2002. Manufactured by Conceptus.
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From page 176... ...
Population Council, New York, NY (http://www.popcouncil.org/)
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FEN ~ 177 Development and FDA Approval Side E~c~ ls, such (~CA) , to Reese Coca Approved ~ Canada and the Nethedands.
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surfactant. amphoteric surfactants cetyl successfu Designed to be betaine and myristamine oxide; and office applied vaginally surfactant/detergent that kills or dose esca before sexual disables pathogens by stripping (PCT)
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From page 179... ...
C31G is now positioned to enter phase III clinical trials for contraception and the prevention of HIV, herpes simplex virus, and chlamydia infections and gonorrhea. Developed by Polydex Pharmaceuticals (Canada)
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dosage have been completed. United K intravaginal gel Phase III clinical trial to be Medicine to prevent HIV conducted in Africa is being infection.
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Two phase I safety studies were completed by the Global Microbicide Project (GMP) ; an acceptability trial for use with diaphragm is planned for 2004.
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From page 182... ...
Sponsored Designed to be applied vaginally before sexual intercourse. PRO2000 Microbicide gel; Unknown; Unlike other sulfonated polymers, Clinicalb (naphthalene adsorption potential such as dextransulfate,which act Indevus I 2-sulfonate inhibitor.
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From page 183... ...
polymers, which act up of ~ 2000 and 'O-CD4 a physical and other fig the lotion function interferes rat RNA Clinical trials undertaken by NIH, HPTN, and Indevus Pharmaceuticals. Phase I clinical trials, conducted in Europe, found that PRO 2000 was well tolerated by healthy, sexually abstinent women.
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From page 184... ...
has not provided guidance on how best to test the safety and efficacy of microbicides in clinical trials. At a recent meeting of an FDA advisory panel, the group discussed whether tests of microbicides should compare the product to condom use or to an inactive placebo, or both.
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From page 185... ...
UPDATE ON MALE CONTRACEPTION Hormonal Methods Before the 1960s, when oral contraceptives and intrauterine devices (IUDs) were introduced, the most commonly used contraception methodscondoms and withdrawal were male directed.
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From page 186... ...
Reversibility is the primary attraction of hormonal methods. Approximately 3,000 men have participated in clinical trials of male hormonal contraceptive methods over the last 20 years, and none of them has failed to return their sperm counts to normal and eventual fertility.3 One limitation of such methods is the slow onset and offset of action from 1 to 4 months because of the hormones' delayed effects on spermatogenesis in the testes.
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From page 187... ...
. In one study, which compared testosterone alone to the same dose of testosterone enanthate combined with oral levonorgestrel, the progestin showed a clear additive effect on the rapidity and completeness of suppression of sperm production compared with the effect of testosterone alone (Bebb et al., 1996~.
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DMPA + hence sperm production.
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From page 189... ...
Approved for use as an anticancer drug. Population Council developed two synthetic analogs that are antispermatogenetic and nontoxic in rats.
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Testosterone Male Suppresses GnRH secretion and Efficacy s undecanoate hormonal thus sperm production.
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Phase I and phase II trials completed in India. Currently in phase III clinical trials.
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This combination can be used to achieve azoospermia in a variety of ways, but one approach is to use a GnRH antagonist like acyline for a brief period such as 12 weeks at the initiation of a regimen to help with suppression of sperm production and then to stop the antagonist and use testosterone enanthate alone. Nonhormonal Methods Various orally active nonhormonal agents have been found in animal models to interfere with spermatogenesis without reducing testosterone levels.
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From page 193... ...
These are examples of exciting new contraceptive agents already at the proof-of-concept stage and merit further support as potential second-generation nonhormonal male contraceptives. UPDATE ON ANTIPROGESTINS AS FEMALE HORMONAL CONTRACEPTIVES The first antiprogestin was discovered in 1980.
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From page 194... ...
A number of studies have demonstrated that 200 mg of mifepristone given in the early luteal phase slows endometrial development without altering the timing of the next menses. Two studies have demonstrated greater than 95 percent contraceptive efficacy of 200 mg of mifepristone given within 2 days of the LH surge (Gemzell-Danielsson et al., 1993; Hapangama et al., 2001~.
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From page 195... ...
Three main considerations that are critical to the success of such an immunological approach are the length of time that antibodies will be effective, the reversibility of the immunocontraceptive, and the hypothetical potential for teratogenicity during periods when antibody levels are declining. At the time, there was great enthusiasm for a vaccine approach, which was novel and different from available contraceptive approaches, and WHO was supporting the work of about 30 scientists.
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From page 196... ...
First, hCG has a clearly defined biological function that depends on its secretion into the maternal circulation, where it is readily accessible to antibodies. Circulating antibodies can act on the circulating hormone, and one does not have to be concerned with raising adequate antibody levels in an organ such as the fallopian tube or the uterus, which would be the case with many other potential antigens.
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From page 197... ...
Other targets and formulations for contraceptive vaccines are also under investigation, but thus far, proof of concept has not been firmly established (reviewed by Gupta, 2003~. Because immunocontraception could provide an alternative and novel method of fertility regulation, funding should be made available to establish proofs of concept for the most advanced and promising leads, based on sound science, to move the field forward.
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In ongoing trials of sperm antigen vaccines, antibody levels will be measured in the female reproductive tract secretions, followed by fertility studies with monkeys after active immunization (primary injection with two boosts)
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Hum Reprod 15~3~:646-649. Global Microbicide Project.
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Hum Reprod 14~11~:2788-2790. Martin CW, Anderson RA, Cheng L, Ho PC, van der Spuy Z
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1996. Contraceptive efficacy of testosterone-induced azoospermia and oligozoospermia in normal men.
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