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Nursing Pharmacology: Antiviral Drugs
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Antiviral Drugs
Anti-viral drugs with activity against HIV (Human Immunodeficiency Virus)
Viral Transmission2
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HIV is mainly transmitted by sexual contact (both heterosexual and male to male); by blood and blood products and by infected mothers to infants (intrapartum, perinatally or by means of breast milk). No evidence exists suggesting that HIV may be transmitted by casual contact or that the virus can be spread by insects (e.g. mosquito bite).2
HIV infection is mainly an STD (sexually transmitted disease) worldwide.
The most common infection mode, especially in developing countries, is heterosexual transmission.
In many Western countries, an increase in incidence of male-to-male sexual transmission has developed.
The likelihood of heterosexual HIV transmission is influenced by viral load as well as by presence of ulcerative genital diseases; however heterosexual transmission is usually inefficient.
A major study considered 174 monogamous couples in which one partner was HIV-1 positive.
The study involved a population in Rakai, Uganda.
Intercourse frequency and reporting reliability within couples were evaluated prospectively.
HIV-1 seroconversion was determined in uninfected partners.
HIV-1 viral load was measured in infected partners. Rates of HIV-1 transmission per coital was determined.
The study reported that the mean intercourse frequency was 8.9 per month, declining both with age and HIV-1 viral load.
Members of couples reported comparable intercourse frequencies.
The overall
unadjusted likelihood of HIV-1 transmission per coital act was 0.0011
i.e. about 0.11%.
The transmission likelihood increased from about 0.01% per act and viral loads less than 1700 viral copies/ml to 0.23% per coital act at 38,500 copies/ml or more.
A higher likelihood of transmission per coital act was noted if genital ulcer disease was present in the HIV-1 positive partner (0.41% vs 0.11%.)
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The presence of HIV in seminal fluids within infected mononuclear cells and in cell-free material has been shown.2
Viral concentration in the seminal fluid appears enhanced under circumstances associated with increased lymphocyte and monocyte number in the fluid.
Urethritis and epididymitis, seen with other sexually transmitted diseases as well, represent such circumstances.2
An
increased risk of HIV transmission has been associated with unprotected
receptive anal intercourse (URAI), affecting both men and women when
compared to the risk associated with receptive vaginal intercourse.2
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Despite the vaginal mucosal structure being several layers thicker than rectal mucosa and accordingly more resistant to being traumatized during intercourse, the HIV-1 virus may be transmitted to either partner during vaginal intercourse.
Clinical studies suggest that male-to female HIV transmission is likely more efficient than female-to-male transmission.
Such differences may be due to longer seminal fluid vaginal-cervical mucosal exposure.
On the other hand, the penis and urethral orifice are exposed only briefly to infected vaginal fluid.2
Cofactors which have been examined as possibly affecting heterosexual HIV transmission include concurrent infection with other STDs.2
This cofactor appears strongly associated with HIV transmission.
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Other pathogens that cause nonulcerative inflammatory sexually transmitted diseases are also associated with elevated HIV transmission infection risk.
Examples of these pathogens include:
Chlamydia trachomatis
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Neisseria gonorrhoeae
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Trichomonas vaginalis
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Oral Sex:2
Oral sex is considered a significantly less efficient transmission mode of HIV compared to anal intercourse or vaginal intercourse.
Given reports of documented HIV transmission as a result of oral sex, any assumption that oral sex is completely safe is not supported.2
HIV transmission risk and drug use:2
HIV transmission risk appears also increased when associated with alcohol consumption, illicit drug use combined with unsafe heterosexual and homosexual behavior.
Taking certain drugs such as methamphetamine as well as
other "so-called club drugs"-e.g., ecstasy,
ketamine, gamma hydroxybutyrate, possibly in
conjunction with phosphodiesterase-5 inhibitors (e.g.
sildenafil (Viagra), tadalafil (Cialis) or vardenafil
(Levitra) appears associated with risky sexual practices
and attendant elevated HIV infection risk (particularly in
male-to-male sex).2
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