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Hydroxychloroquine is used in treatment of conditions as Rheumatoid arthritis Inflammatory osteoarthritis Discoid and systemic lupus erythematosus Dermatological conditions caused or aggrevated by sunlight Malaria- suppressive treatment and treatment of acute attacks of malaria due to Plasmodium vivax, P.malariae , P.ovale , and susceptible strains of P.falciparum

PLAQUENIL® 200 mg Film coated Tablets- usual dose is 200-400 mg daily ( not exceeding 6.5 mg/ kg body weight )

Mechanism of action- Quinine is the parent molecule ( antimalarial )
Antimalarial action not discussed here
 Precise mechanism of action not known ( Anti rheumatoid arthritis )
Several pharmacological actions may be involved -
○ interaction with sulphydryl groups
○ inhibiting activity of many enzymes including collagenase and proteases that cause cartilage breakdown
○ Bind and alter DNA
○ stabilisation of lysosomal membranes
○ inhibition of prostaglandin formation
○ inhibition of polymorphonuclear cell chemotaxis and phagocytosis
○ possible interference with interleukin 1 production from monocytes
○ inhibition of neutrophil superoxide release

Resulting in immunomodulatory and immunosuppressive effects
 Cumulative in action ie will require several weeks to exert its beneficial effect , whereas minor side effects may occur relatively early

Cautions – adverse effects Gastrointestinal – nausea , diarrhoe , anorexia and abdominal pain
 Skin -rashes , pruritis , pigmentary changes in skin and mucous membrane , bleaching of hair and alopecia ( resolve on stopping )
 CNS- less frequently , dizziness , vertigo , tinnitus , hearing loss , headache . nervousness , emotional liability , toxic psychosis and convulsions have been reported
 Neuromuscular-skeletal muscle myopathy or neuromyopathy leading to progressive weakness and atrophy of proximal muscle groups

Before starting treatment –FBC U & E s LFTs Visual impairment ( not corrected by glasses ) Record near visual acuity using a standard reading chart ( with reading glasses if worn ) Formal retinal assessment advised by latest guidance 
( local agreements availability will vary )

Primary care monitoring –
Royal College of Ophthalmologists recommends an annual review
 either by an optometrist or by enquiring about visual symptoms rechecking visual acuity assessing for blurred vision using the reading chart

People requiring long-term therapy ( 5 yrs ) → discuss with ophthalmologist

Ocular side effects –Ocular complications with Hydroxychloroquine ( HCQ ) therapy are rare but potentially serious Risk ↑ es with duration of use and appears dose dependent Complications include both corneal and retinal disease Retinopathy – with changes in pigmentation and visual field defects can occur 
( uncommon if recommended daily dose is not exceeded )
○ early form reversible on disontinuation of HCQ
○ if allowed to develop there may be risk of progression even after treatment withdrawal
○ asymptomatic initially or may have scotomatous vision and abnormal colour vision
 Corneal changes -oedema and opacities
○ May cause disturbances as haloes , blurring of vision or photophobia
○ may be transient and reversible on stopping treatment
○ blurring of vision due to a disturbance of accomodation is dose dependent and is reversible
 Identified baseline risk factors for ocular complications include old age , renal disease and pre existing retinal disease

Notable interactions –Antacids- reduced absorption of HCQ , do not take within 4 hrs Amiodarone ↑ ed risk of ventricular arrythmias ( avoid concomitant use) Antibiotics aminoglycoside potentiation of its direct blocking action at neuromuscular junction Antipsychotics ( droperidol ) Cimetidine may ↑ plasma conc Ciclosporin ↑ levels risk toxicity Digoxin ↑ plasma digoxin levels Rabies vaccine ( intraderma human diploid cell ) ↓ of antibody response to primary immunisation




Plaquenil – Hydroxychloroquine information from Medicine compendium

Vesrsus arthritis on HCQ

Australian Rheumatology Association on HCQ

American College of Rheumatology on HCQ-1 page PIL

British Association of Dermatology on HCQ

New Zealand Medicine and Medical Devices Safety Authority PIL on HCQ 1 page printable concise leaflet

Web MD on HCQ


Check for interactions on Drugs com webpage on HCQ

Excellent work by PubChem US National Library of Medicine – all you would want to know about HCQ


Therapy and pharmacological properties of hydroxychloroquine and chloroquine in the treatment of systemic lupus erythematosus, rheumatoid arthritis and related diseases Rainsford, K.D., Parke, A.L., Clifford-Rashotte, M. et al. Inflammopharmacol (2015) 23: 231.

References –

  1. Suggestions for Drug Monitoring in Adults in Primary Care ; A collabration between London and South East Medicine Information Service , South West Medicine Information Service and Croydon Commissioning Group February 2014
  2. Pharmacology of Chloroquine and Hydroxychoroquine DJ Browning Springer Com
  3. Shared care Guideline Hydroxychloroquine York Teaching Hospital NHS Foundation Trust
  4. DMARDs Scenario: Hydroxychloroquine accessed via!scenario:6 Medicine Compendium
  5. Hydroxychloroquine accessed via
  6. BSR / BHPR Non-Biologic DMARD Guidelines
  8. 2015 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthrits Jasvinder A.Singh et al Arthritis Care and Research DOI 10.1002/acr.22783
  9. BNF via


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