Quinacrine (QE)

  • (Cat. C)
  • (no cross allergy with HCQ or CQ)

  • Available as 100 mg powder (compounded)
  • Start 50 mg

  • As above +
  • Concentrates in lysosome → inhibits B-Lymphocyte stimulator

  • Can be combined with HCQ or CQ, response in 6-8 weeks, if no response then discontinue

Absolute

  • Hypersensitivity
  • Retinopathy

Relative

  • Pregnancy
  • Lactation
  • Retinal/visual field changes
  • Severe blood dyscrasias
  • Significant Hepatic disorder
  • Significant Neurologic impairment e.g. myasthenia gravis 
  • Psoriasis (may lead to erythrodermic psoriasis)

  • Aplastic anemia
  • Agranulocytosis
  • True retinopathy→ no risk with QE
  • Can cause hypohidrosis by destruction of eccrine glands

↓ Efficacy

  • Smoking (dose-dependant)
  • Antacids (↓ absorption)

↑ Toxicity

  • HCQ + CQ = retinal toxicity
  • Local anesthetics (benzocaine, prilocaine): ↑Methemoglobenemia
  • Cimetidine (↓ metabolism)

Antimalarial ↑ toxicity of

  • Cyclosporine
  • Digoxin
  • Antiarrhythmics

Baseline

  • Baseline eye exam (within 1st year): slit lamp, Funduscopy, visual fields & acuity
  • CBC, chemistry profile, creatinine, LFT
  • G6PD (with 8- aminoquinolines mainly/ Unnecessary to screen for G6PD due to low risk of hemolysis at doses of antimalarials utilized in dermatology) +/- urine porphyrins

FU

  • CBC, LFT, creatinine qmonthly x3months, then q3-6months
  • Eye exam annually after 5 years of use

Retinopathy risk factors

  • Cumulative dose & daily dose
  • Elderly (> 60 years)
  • Impaired liver &/or renal function 
  • Pre-existing macular/retinal disease
  • Tamoxifen with HCQ
  • HCQ + CQ combined

Notes

  • Half-life 40-50 days (except QE 1-2 weeks)
  • Likes melanin rich tissue (skin & retina) 
  • Response seen within 2-3 months
  • Should be continued in pregnant systemic lupus patients as benefits out-weight risks (↓ risk of clots & neonatal lupus heart block)
  • Skin pigmentation on histopathology → hemosiderin around capillaries & dermal melanin
  • Highest risk for drug eruption (HCQ) is with anti-SAE DM & no risk with anti- MDA-5 DM (1)