Pharmacology for STDs: Sweatman Flashcards
How do we treat:
HSV
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Acyclovir or Valacyclovir or Famciclovir*
MOA: competitively inhibits viral DNA polymerase
AEs: neurotoxicity incl seizures for acyclovir/valacyclovir
Special considerations: Patient needs to be well hydrated to avoid crystalline nephropathy or neurotoxicity
NOTE: Decreased viral thymidine kinase or mutation in DNA polymerase lead to RESISTANCE
*famciclovir does not cause chain termination
How do we treat:
Primary Syphilis: Treponema palladium
And Latent Syphilis
And congenital syphilis
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Benzathine Penicillin G, IM
MOA: Bactericidal beta-lactam: binds PBPs causing cell lysis
AEs: Hypersensitivity or skin rashes may be problematic
Contraindications:
Note: Poor penetration of CSF - not good for treatment of
neurosyphilis
Latent Syphilis: Benzathine Pen G
Congenital syphilis: Aqueous crystalline Penicillin G or Procaine Penicillin G
Note about tx w/ penicillin: Jarisch-Herxheimer Reaction
Observed in most patients (70-90%) with secondary
syphilis several hours after first injection of penicillin
Chills, fever, headache, myalgias, and arthralgias
• Syphilitic cutaneous lesions may become more
prominent, edematous, and brilliant in color. Do NOT discontinue tx. Due to release of spirochetes from cells and subsequent host rxn to products.
How do we treat:
Chlamydia
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Azithromycin or Doxycycline or Erythromycin base or Levofloxacin or Ofloxacin
Alternative in pregnancy is Amoxicillin
MOA:
Az: Binds 50S ribosomal subunit: bacteriostatic. AEs: GI upset; vaginitis
Doxy: Binds 30S ribosomal subunit: bacteriostatic. AEs: GI upset; hepatic damage in high dose esp in
pregnancy; photosensitivty with sunlight or tanning bed. Cat. D.
Eryth: Binds 50S ribosomal subunit: bacteriostatic. AEs: GI upset; increases toxicity of CYP3A4 substrates;
estolate preparations may cause cholestatic jaundice;
risk of sudden cardiac death with CYP3A4 inhibitors
Levoflox: Inhibits DNA gyrase (topo II) in gram-negative:
bactericidal. AEs: Taste disturbance (levo); GI upset; BBW of ^ risk of tendonitis & rupture; BBW of exacerbation of muscle weakness – avoid with myasthenia gravis. Cat. C.
Oflox: Inhibits topo IV in gram-positive: bactericidal. AEs: same as for levo.
Amox: Bactericidal beta-lactam: binds PBPs causing cell lysis
How do we treat:
Chancroid (Hemophilus ducreyi)
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Azithromycin: Binds 50S ribosomal subunit: bacteriostatic. AEs: GI upset; vaginitis
Ceftriaxone: Bactericidal beta-lactam: binds PBPs causing cell lysis
Ciprofloxacin: Inhibits DNA gyrase (topo II) in gram-negative: bactericidal
Inhibits topo IV in gram-positive: bactericidal.
Contraindicated in pregnancy and lactation
Erythromycin: Binds 50S ribosomal subunit: bacteriostatic. AEs: GI upset; increases toxicity of CYP3A4 substrates; estolate preparations may cause cholestatic jaundice; risk of sudden cardiac death with CYP3A4 inhibitors
How do we treat:
Gonorrhea: cervix – urethra – rectum – pharynx
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Gonorrhea: below the belt:
Ceftriaxone or Cefixime + Azithromycin or Doxycycline
MOA: Cefixime: Bactericidal beta-lactam: binds PBPs causing cell lysis
AEs: Cefixime: Diarrhea & GI upset. Rarely may ^ clotting time.
False positive for urinary glucose in diabetic patients
Gonorrhea: above the belt:
Ceftriaxone + Azithromycin or Doxy
How do we treat:
Urethritis-Cervicitis as well as recurrent treatment
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Same as Chlamydia
Azithromycin or Doxycycline or Erythromycin base or Levofloxacin or Ofloxacin
Recurrent: Metronidazole or Tinidazole + Azithromycin
How do we treat:
Trichomoniasis
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Metronidazole or Tinidazole
MOA: Amebicidal, bactericidal, and trichomonacidal
Unionized drug taken up by anaerobic organisms and cells
where it is reduced to its active form which disrupts DNA’s
helical structure, thereby inhibiting bacterial nucleic acid
synthesis. Equally effective vs. dividing and non-dividing cells
AEs: Avoid in pregnancy and breastfeeding; GI upset; candidiasis; disulfiram-like effect (avoid alcohol for 24 hr (M) or 72 hr (T) AFTER completing therapy; 2° malignancies in animal model
How do we treat:
Candidiasis
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
A bunch of azoles.
MOA: vaginal gels or fluconazole orally. Blocks ergosterol synthesis through interacting with 14-alpha
demethylase, a CYP necessary conversion of lanosterol to
ergosterol; essential membrane component
AEs: High systemic doses of azoles (100-750 mg/kg/day) produce abdominal wall defects & cleft palate in fetus & maternal stress
– Recommended avoid in 1st trimester
How do we treat:
Bacterial vaginosis
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Metronidazole or Clindamycin or Tinidazole
MOA: Clindamycin Binds 50s ribosomal subunit to inhibit protein synthesis;
bacteriostatic
Contraindications: Clindamycin: Intravaginal delivery only before 16 wks gestation due to R/O PROM, low birth weight, premature delivery.
AEs: Clindamycin: GI upset most commonly with systemic drug BUT also reported with
intravaginal application. Local delivery also rarely associated with contact
toxicity
How do we treat:
HPV and genital warts
Explain the mechanism of drug action, basic
pharmacology and any issues regarding adverse effects
or significant contraindications
Prevention: Gardasil & Cervarix
Both contain recombinant L1 protein, the major antigenic
protein of the capsid of HPV
– Gardasil: types 6, 11, 16, & 18 (quadrivalent)
– Cervarix: types 16 & 18 (bivalent)
Possible hypersensitivity rxn. No further doses if occurs.
Genital warts: 90% caused by HPV 6 & 11
Podofilox a plant-derived mitotic spindle
inhibitor blocking microtubular activity in keratinocytes
Imiquimod an immune response modifier
Sinecatechins a green tea extract antioxidant
