What is the structure/class of tetracycline?
First-generation tetracycline antibiotic (class: tetracyclines). [expanded for LO1]
How is tetracycline absorbed and what are its routes?
Oral immediate-release; better absorbed fasting; food reduces by ~10-20% (acceptable). Divalent cations in dairy, vitamins, antacids, antidiarrheals reduce absorption.
What is the half-life and bioavailability of tetracycline?
6-12 hours; class is lipophilic with skin and nail penetration; all IR formulations.
How is tetracycline metabolised and excreted?
Renal adjustment required for tetracycline; absorption reduced by metals; excretion primarily renal. [expanded for LO1]
What is the mechanism of action of tetracycline?
Bacteriostatic; binds 30S ribosomal subunit inhibiting protein synthesis; anti-inflammatory effects including reduced neutrophil chemoattractant, anti-neutrophilic, anti-granuloma, downregulates cytokines.
What are the indications/contexts for tetracycline?
Acne vulgaris, perioral dermatitis (1–3 months), various inflammatory/dermatology indications alongside doxy/mino in class.
What are the contraindications/precautions for tetracycline?
Hypersensitivity; children <9 years; pregnancy/lactation (Category D; contraindicated in 2nd and 3rd trimester). Renal adjustment needed.
What are adverse effects of tetracycline?
GI nausea and vomiting; pill oesophagitis risk; photosensitivity; secondary infection (vaginal candidiasis, gram-negative folliculitis); pseudotumour cerebri; hypersensitivity (SJS/TEN).
What are important drug interactions for tetracycline?
Retinoids increase risk of pseudotumour cerebri; metallic ions reduce absorption; OCP efficacy possibly reduced (recommend second contraception).
What are clinical pearls for tetracycline?
Use with topical benzoyl peroxide/retinoids (avoid monotherapy); stewardship: shortest effective course with review at 3–4 months.
What is the structure/class of doxycycline?
Second-generation tetracycline antibiotic; more lipophilic than tetracycline. [expanded for LO1]
How is doxycycline absorbed and what are its routes?
Oral immediate-release; better fasting; food reduces absorption by ~10–20% (acceptable). Better GI absorption than tetracycline; widely used in derm.
What is the half-life and bioavailability of doxycycline?
6-22 hours; class penetrates skin and nails, crosses blood–brain barrier; lipophilicity: minocycline > doxycycline > tetracycline. [expanded for LO1]
How is doxycycline metabolised and excreted?
Metabolised in liver and excreted via GI tract (biliary/faecal). Renal adjustment not required per file note (‘doxycycline ok’).
What is the mechanism of action of doxycycline?
Bacteriostatic 30S inhibition plus anti-inflammatory actions: reduces neutrophil chemoattractant from P. acnes; anti-neutrophilic; anti-granuloma; cytokine downregulation.
What are the indications/contexts for doxycycline?
Acne vulgaris (100 mg daily; visible improvement ~3 weeks, ~50% by 12 weeks, 70–90% overall); rosacea 50–100 mg twice daily 4–12 weeks; perioral dermatitis 1–3 months; multiple inflammatory/autoimmune dermatoses with class.
What are the contraindications/precautions for doxycycline?
Hypersensitivity; children <9 years; Category D (CI 2nd/3rd trimester). Liver disease precaution (listed for doxycycline).
What are adverse effects of doxycycline?
GI upset and pill oesophagitis (higher with doxycycline); photosensitivity; secondary infection (vaginal candidiasis, gram-negative folliculitis); pseudotumour cerebri; hypersensitivity (SJS/TEN).
What are important drug interactions for doxycycline?
Retinoids → pseudotumour cerebri; metallic ions reduce absorption; OCP efficacy controversial (recommend second contraception).
What are clinical pearls for doxycycline?
Advise large water intake and avoid reclining to reduce pill oesophagitis; stewardship: limit systemic antibiotics to shortest duration with review at 3–4 months.
What is the structure/class of minocycline?
Second-generation tetracycline; most lipophilic of the class. [expanded for LO1]
How is minocycline absorbed and what are its routes?
Oral immediate-release; better fasting; food reduces by ~10–20% (acceptable). High lipophilicity → high skin, nail, and CNS penetration.
What is the half-life and bioavailability of minocycline?
11.1-22.1; class crosses blood–brain barrier; lipophilicity ranking: minocycline > doxycycline > tetracycline. [expanded for LO1]
How is minocycline metabolised and excreted?
Excreted renally; renal adjustment required. Liver disease precaution listed for class; monitor with FBC/chemistry/LFTs (no exact guideline provided).
