Sulfonamides
· Sulfonamides are classified as bacteriostatic
· Inhibit bacterial synthesis of folic acid which is required for bacterial growth (p.441)
· Clinical uses of sulfonamides
o Urinary tract infections
§ Escherichia coli
o Meningococcal meningitis
o Chlamydia
o Toxoplasma gondii
o Absorbed by the GI tract
o Distributed to body tissues and the brain
o Metabolized by the liver
o Excreted by the kidneys
o Availability
§ Oral
§ Solution
§ Ointment (ophthalmic use)
§ Cream (for burns)
o Highly protein bound
o Short- acting sulfonamides
§ Rapid absorption and excretion
o Intermediate-acting sulfonamides
§ Moderate to slow absorption and slow excretion rate
o Some older sulfonamides are low soluble
§ May cause crystallization in the urine
· May cause hematuria and kidney damage
o Newer sulfonamides are more water soluble
§ Crystallization and kidney damage are less likely
o Skin rash/itching
o Hemolytic anemia, aplastic anemia, decreased WBC and platelets
o Anorexia, nausea, vomiting
o Photosensitivity
o Pregnancy—especially third trimester
o Severe renal or hepatic disease
o Drink with full glass of water
o Avoid long exposure to sunlight
o Anaphylaxis is not common
Safe Administration of Sulfonamides
Ø In clinical use since 1935.
Ø First drugs used against bacteria (they are bacteriostatic & are not considered antibiotics).
Ø It is rare to use sulfonamides alone. They are almost always combined with other drugs.
Sulfadiazene
Ø Used for prophylaxis of streptococcus in patients with rheumatic fever who are hypersensitive to penicillin. It may form urinary crystals which can damage kidneys. Therefore, increased fluid intake is recommended. More modern sulfonamides are less apt to cause crystallization.
Trimethoprim & Sulfamethoxazole
Ø Both drugs given together slow the development of bacterial resistance.
Ø Synergistic Effect.
Ø Effectively treats UTI, GI, and lower respiratory bacterial infections, otitis media, prostatitis, & gonorrhea.
Ø Prevents Pneumocystis carinii in AIDS patients.
Ø Increased fluid intake recommended.
Ø Side Effects: N/V/D, rash, stomatitis, anorexia, fatigue, depression, headache, vertigo, photosensitivity.
Ø Contraindications: Renal/Hepatic disease, hypersensitivity to sulfonamides.
Ø Rare but serious adverse effects: agranulocytosis, aplastic anemia, allergic myocarditis.
Topical & Ophthalmic Sulfonamides
Ø Infrequently used because they can cause hypersensitivity reactions.
Ø Mafenide acetate (Sulfamylon) is used to prevent sepsis in burns.
Ø Silver sulfadiazine (Silvadene) is also used to treat burns.
Ø Sulfacetamide sodium (AK-Sulf, Cetamide, Sodium Sulamyd, Sulf-10) is used for conjunctivitis and corneal ulcers. It is also used prophylactically for eye trauma or foreign body removal. Topical compounds are used to treat seborrheic dermatitis and secondary bacterial skin infections. It is important to only use topical preparations for the skin and only use ophthalmic preparations for the eye.
From epocrates.com
Kava + sulfamethoxazole may increase risk of hepatotoxicity
St. John’s Wort + sulfamethoxazole may theoretically increase risk of skin photosensitivity
Black cohosh + sulfamethoxazole may increase risk of hepatotoxicity
Black cohosh + sulfadiazine may increase risk of hepatotoxicity
Kava + sulfadiazine may increase risk of hepatotoxicity
St. John’s Wort + sulfadiazine may increase risk of photosensitivity
References
Cosinuke, R. (2014). Retrieved from Epocrates website: http://www.epocrates.com
Kee, J. L., Hayes, E. R., & McCuistion, L. E. (2012). Pharmacology. A nursing process approach. St. Louis, MO: Elsevier.
One thing left out of significance is that sulfa drugs can interact with other medications, especially warfarin. This is a severe interaction that results in elevated INRs. Monitor close and down dose the warfarin. Bactrim DS is often given 1 tab bid for most indications but is also given for community acquired MRSA at 2 tabs bid (in larger patients).
ReplyDeleteThank you so much for the response. For patients who are on warfarin and only require monthly blood draws, if placed on a sulfa drug is it common that these patients are instructed to receive more frequent blood draws for the duration of the sulfa treatment? Again, thank you for the response; it is much appreciated.
ReplyDeleteAny time a new drug is added to patients receiving warfarin, they should have closer monitoring of INRs. There are over 200 different drug interactions with warfarin and each person will respond differently. Monitoring is key.
ReplyDeleteThat is very good to know. Thank you so much.
ReplyDelete