L20 - Drugs used in sexually transmitted diseases

Question 1

Pharmacology of bacterial STDs vs viral STDs

Answer 1

STDs caused by bacteria can be treated and cured with antibiotics (e.g. Chlamydia, Gonorrhoea, syphilis)

STDs caused by viruses can only be controlled but not cured (e.g. genital herpes, genital warts, HIV infections)

Question 2

Chlamydial infections (manifestation, empirical treatment, ADR)

Answer 2

Manifestation: Urethritis and cervicitis Empirical

Treatment:

1) Azithromycin (1g orally in a single dose) or
2) Doxycycline (broad spectrum; 100mg orally twice daily for 7 days)

[use azithromycin in case of pregnancy]

ADR: 1) Mostly gastrointestinal (mild to moderate)

2) Affects bone formation in pregnancy

Question 3

Azithromycin mechanism

Answer 3

Concentrated in infected cells to kill intracellular bacteria

Question 4

Why doxycycline not used in pregnancy

Answer 4

Doxycycline binds to calcium ions, therefore affect bone formation of foetus

Question 5

Gonococcal infection (manifestation, treatment, complications)

Answer 5

Manifestation: Urethritis and cervicitis

Treatment:

1) A single intramuscular injection of ceftriaxone in combination with a single oral dose of azithromycin -> highly effective against penicillin- and tetracycline-resistant strains of Neisseria gonorrhoea
2) Oral cephalosporin or fluoroquinolones - no longer recommended by Centres for Disease Control (CDC) as a first-line therapy due to increased resistance

Complications: May cause Pelvic Inflammatory Disease (PID) if not treated successfully

Question 6

Pelvic Inflammatory Disease (Definition, cause, epidemiology, treatment regimens, complications)

Answer 6

Definition: Ascending infections that affect the upper female reproductive tract

Cause: Chlamydia trachomatis, Neisseria gonorrhoea and/or anaerobic bacteria

Epidemiology: Sexually active women

Treatment Regimens:

1) Inpatient empiric parenteral regimen
2) Outpatient regimen

Complications: Ectopic pregnancy or infertility if not treated

Question 7

PID Inpatient parenteral regimen

Answer 7

• Should provide broad spectrum antimicrobial coverage - e.g.IV cefoxitin or cefotetan with oral doxycline; or - clindamycin with an aminoglycoside (IV)

Question 8

PID outpatient regimen

Answer 8

• Include ceftriaxone (single IM dose) - plus oral doxycycline ± metronidazole for 14 days

Question 9

Why cefoxitin or cefotetan used in PID inpatient parenteral regimen

Answer 9

Second generation cephalosporin -> broader antimicrobial coverage

Question 10

Why metronidazole used in PID outpatient regimen

Answer 10

For the elimination of anaerobic bacteria

Question 11

Forms of Vaginal infections

Answer 11

1) Bacterial vaginosis (BV)
2) Trichomoniasis (TV)
3) Vulvovaginal candidiasis (VVC)

Question 12

Vaginal infection risk factor

Answer 12

Poor personal hygiene

Question 13

Bacterial Vaginosis (pathogen, treatment)

Answer 13

Pathogen: Anaerobic bacteria

Treatments:

1) standard treatment with oral metronidazole for 7 days; or
2) metronidazole gel applied intravaginally; or
3) Clindamycin (oral/intravaginal)

Question 14

Trichomoniasis (Pathogen, treatment)

Answer 14

Pathogen: protozoan parasite (i.e. trichomonas vaginalis)

Treatment:

1) single dose of metronidazole or tinidazole

Question 15

Vulvovaginal candidiasis (Pathogen, treatment)

Answer 15

Pathogen: Fungal pathogen (e.g. candida albicans)

Treatment:

1) Topical drugs to resist candida overgrowth
2) e.g. azole antifungal agents (fluconazole)

Question 16

Syphilis treatment

Answer 16

1) Usually treated with parenteral pencillin G for all stages of syphilis
2) Long-acting preparations of penicillin available to achieve relatively slow release of pencillin G into circulation (e.g. a singel intramuscular injection of benzathine penicillin G for early latent stage.

Question 17

Benzathine pencillin G characters

Answer 17

A form of a complex to enhance duration so penicillin (with short half-life) is released/dissociated slowly into the bloodstream

Question 18

:ebelling: Benzathine pencillin, Penicillin G (IM), Pencillin G (oral), Procaine penicillin

Answer 18