Lincosamides

Lincosamides may not be frontline antibiotics in community practice, but they’re a crucial option for patients with β-lactam allergies and for anaerobic coverage. Pharmacists—especially interns—must understand their nuances, toxicities, and proper use to optimise patient outcomes and avoid harm.

General Principles of Link:

Anti-Infectives

Medicine Link

1. Clindamycin

2. Lincomycin

3. Clinda + Tretinoin

Summary Snapshot – Intern Pharmacist Quick Table

Drug	Route	Use	Key Risks	Key Tip
Clindamycin	Oral/IV/topical	β-lactam allergy, anaerobes	Diarrhoea, C. difficile	Monitor with long use
Lincomycin	IV/IM only	β-lactam allergy	Cross-resistance, limited activity	Rarely used
Clinda + Tretinoin	Topical	Inflammatory acne	Sun sensitivity, dryness	Use sunscreen, short-term only

Mechanism of Action

Both clindamycin and lincomycin are bacteriostatic antibiotics that:

• Inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit

• Exhibit cross-resistance with macrolides and each other

• Are active mainly against Gram-positive cocci and anaerobes

Where They Fit In

Drug	Routes	Brands (AU)	Common Use
Clindamycin	Oral, IV, Topical, Vaginal	Dalacin C®, Clindagel®	Skin, bone, dental, PJP, BV
Lincomycin	IV/IM only	Lincomycin Sandoz®	Rarely used – severe β-lactam allergy

Clinical Indications

Clinical Use	Notes
Penicillin/cephalosporin allergy	For skin, soft tissue, dental, aspiration pneumonia
Anaerobic infections	Particularly intra-abdominal or aspiration-related
Bacterial vaginosis (BV)	Oral or topical clindamycin
Toxoplasma encephalitis	Combined with pyrimethamine
PJP (Pneumocystis jirovecii pneumonia)	With primaquine
Surgical/endocarditis prophylaxis	In select high-risk β-lactam-allergic patients
Topical acne	With or without tretinoin

Use in Special Populations

Group	Recommendation
Pregnancy	✅ Safe (clindamycin) – except clindamycin+tretinoin combo (avoid due to retinoid)
Breastfeeding	✅ Safe – may cause mild infant diarrhoea
Children	Use weight-based dosing; watch for C. difficile
Renal/Hepatic Impairment	Monitor with prolonged use (esp. >10 days)

Adverse Effects – What Pharmacists Should Watch For

Type	Common	Infrequent	Rare
GI	Diarrhoea, nausea, abdominal cramps	C. difficile colitis	Liver injury, AKI
Skin	Rash, itch	–	SJS, TEN
Systemic	–	–	Anaphylaxis, blood dyscrasias
IV-specific	–	Thrombophlebitis	Hypotension/cardiac arrest (rapid injection)
IM-specific	–	Injection site pain	Sterile abscess

Dosing Summary – Clindamycin

Clindamycin

Indication	Adult Dose	Route
General infections	150–450 mg q6–8h	Oral
Severe infections	600–2700 mg/day in 2–4 doses (max 4800 mg/day)	IV
Dental infections	300–450 mg q8h for 5–7 days	Oral
PJP	450–600 mg q6–8h	Oral/IV
Toxoplasmosis	600 mg q6h (treatment)	IV
Bacterial vaginosis	300 mg BD × 7 days	Oral
Endocarditis prophylaxis	600 mg 1–2 hrs before procedure	Oral/IV
Surgical prophylaxis	600 mg IV within 2 hrs of incision	IV

Children (Oral): 5–10 mg/kg q8h (max 450 mg)

Children (IV/IM): 5–15 mg/kg q8h (max 600 mg)

Lincocin

Practice Tips

• Full cross-resistance: clindamycin ↔ lincomycin

• Partial cross-resistance with macrolides (check if Staph/Strep resistant)

• C. difficile risk: Clindamycin has higher risk than many antibiotics

• No commercial oral liquid: For paediatrics, dissolve capsule powder in water/juice

• Topical clindamycin: Effective in acne – but use short-term to reduce resistance

Topical Combination – Clindamycin + Tretinoin (Acnatac®)

Actanac

✅ Use: Inflammatory acne (pustules, comedones)

Dose: Apply thin layer once daily at bedtime

Tips:

• Wash & dry face before use

• Use sunscreen daily (tretinoin increases UV sensitivity)

• Stop combo when inflammation clears; continue tretinoin alone for maintenance

• Avoid in pregnancy

Counselling Points – Clindamycin (Oral/IV/Topical)

Form	Key Advice
Oral	Take with food + full glass of water; report diarrhoea
IV	Infuse slowly (≤30 mg/min); monitor BP
Topical (Acne)	Apply thinly; avoid eyes/mouth; expect mild dryness
Vaginal	Apply at bedtime; avoid intercourse during use

Monitoring Parameters

• CBC, renal, and hepatic function if:

  • Using >10 days

  • High doses or IV therapy

• Watch for C. difficile symptoms even weeks after stopping