WYAMYCIN S

Clinical safety rating: caution

Comprehensive clinical and safety monograph for WYAMYCIN S (WYAMYCIN S).

How it works

WYAMYCIN S (tetracycline) inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.

What the body does with it

Metabolism	Primarily metabolized in the liver via glucuronidation; minor metabolism by CYP450 isoenzymes.
Excretion	Renal (90-95% unchanged via glomerular filtration) and biliary (<5%).
Half-life	2-3 hours in normal renal function; prolonged to 24-48 hours in end-stage renal disease.
Protein binding	10-30% bound to serum proteins.
Volume of Distribution	0.25-0.4 L/kg indicating primarily extracellular fluid distribution.
Bioavailability	IM: >90%.
Onset of Action	IM: 1-2 hours; IV: rapid (within 30 minutes).
Duration of Action	6-8 hours (IM/IV) with dose adjustment needed in renal impairment.

Classification & Brands

Dosing & administration

WYAMYCIN S (clarithromycin/sulfamethoxazole) is a fixed-dose combination. Adult: 1 tablet (500 mg clarithromycin/800 mg sulfamethoxazole) orally every 12 hours for 7-14 days.

Dosage form	TABLET
Renal impairment	For CrCl 30-50 mL/min: reduce dose to 1 tablet every 24 hours. CrCl <30 mL/min: not recommended.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B or C: use with caution, monitor for toxicity; no specific dose recommendation.
Pediatric use	Not recommended for children under 12 years due to sulfonamide safety concerns.
Geriatric use	Elderly patients may have age-related renal impairment; adjust dose based on CrCl. Monitor for QT prolongation and electrolyte disturbances.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for WYAMYCIN S (WYAMYCIN S).

Breastfeeding	Excreted in breast milk in low concentrations; M/P ratio not established. Risk of infant gut flora alteration and ototoxicity; avoid breastfeeding or discontinue drug.
Teratogenic Risk	First trimester: Avoid due to potential teratogenicity (aminoglycoside class). Second and third trimesters: Risk of fetal ototoxicity and nephrotoxicity; use only for life-threatening infections when no safer alternatives exist.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to tetracyclines; pregnancy (category D); breastfeeding; children under 8 years; severe hepatic impairment; concomitant use with oral retinoids.

Clinical Precautions

Precautions

Photosensitivity; hepatotoxicity especially in pregnancy or with pre-existing liver disease; renal dysfunction may require dose adjustment; use of outdated tetracycline may cause Fanconi syndrome; C. difficile-associated diarrhea; benign intracranial hypertension; tooth discoloration and bone growth retardation in fetuses/children under 8 years; concomitant use with isotretinoin may increase risk of pseudotumor cerebri.

Clinical Tips & Counseling

Drug interactions

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WYAMYCIN S

Clinical safety rating: caution

Comprehensive clinical and safety monograph for WYAMYCIN S (WYAMYCIN S).

How it works

WYAMYCIN S (tetracycline) inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.

What the body does with it

Metabolism	Primarily metabolized in the liver via glucuronidation; minor metabolism by CYP450 isoenzymes.
Excretion	Renal (90-95% unchanged via glomerular filtration) and biliary (<5%).
Half-life	2-3 hours in normal renal function; prolonged to 24-48 hours in end-stage renal disease.
Protein binding	10-30% bound to serum proteins.
Volume of Distribution	0.25-0.4 L/kg indicating primarily extracellular fluid distribution.
Bioavailability	IM: >90%.
Onset of Action	IM: 1-2 hours; IV: rapid (within 30 minutes).
Duration of Action	6-8 hours (IM/IV) with dose adjustment needed in renal impairment.

Classification & Brands

Dosing & administration

WYAMYCIN S (clarithromycin/sulfamethoxazole) is a fixed-dose combination. Adult: 1 tablet (500 mg clarithromycin/800 mg sulfamethoxazole) orally every 12 hours for 7-14 days.

Dosage form	TABLET
Renal impairment	For CrCl 30-50 mL/min: reduce dose to 1 tablet every 24 hours. CrCl <30 mL/min: not recommended.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B or C: use with caution, monitor for toxicity; no specific dose recommendation.
Pediatric use	Not recommended for children under 12 years due to sulfonamide safety concerns.
Geriatric use	Elderly patients may have age-related renal impairment; adjust dose based on CrCl. Monitor for QT prolongation and electrolyte disturbances.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for WYAMYCIN S (WYAMYCIN S).

Breastfeeding	Excreted in breast milk in low concentrations; M/P ratio not established. Risk of infant gut flora alteration and ototoxicity; avoid breastfeeding or discontinue drug.
Teratogenic Risk	First trimester: Avoid due to potential teratogenicity (aminoglycoside class). Second and third trimesters: Risk of fetal ototoxicity and nephrotoxicity; use only for life-threatening infections when no safer alternatives exist.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

Hypersensitivity to tetracyclines; pregnancy (category D); breastfeeding; children under 8 years; severe hepatic impairment; concomitant use with oral retinoids.