Hydroxychloroquine Dose Calculator
Determines the safe daily dose of Plaquenil based on patient weight.
Refer to the text below the tool for more information about hydroxychloroquine dosing.
Hydroxychloroquine related retinal toxicity manifests through a range of clinical signs, from maculopathy with retinal pigment epithelium (RPE) changes to advanced retinopathy with bull's eye maculopathy (ring of parafoveal RPE depigmentation).
Whilst retinal toxicity from HCQ therapy cannot be completely prevented, effective screening can help recognize patients before significant risk of central vision loss occurs and a review of the safe daily dosage will decrease risk of retinopathy.
The American Academy of Ophthalmology (AAO) revised its guidelines in 2016 to decrease the maximum dosage from 6.5 mg/kg/day to 5 mg/kg/day to minimize retinal toxicity.
Melles and Marmor 2014 study demonstrated that patients whose dose exceeded 5 mg/kg per day had a 10% cumulative risk of developing retinopathy within 10 years (rising to 40% after 20 years).
By comparison, patients on a lower dose of 4 - 5 mg/kg/day had a cumulative risk of 2% within 10 years and 20% risk after 20 years.
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About Hydroxychloroquine (Plaquenil) Dose
Hydroxychloroquine (Plaquenil) is used in the treatment of rheumatoid arthritis, systemic lupus erythematosus, and other autoimmune and dermatological conditions.
HCQ-related retinal toxicity manifests through a range of clinical signs, from maculopathy with retinal pigment epithelium (RPE) changes to advanced retinopathy with bull's eye maculopathy (ring of parafoveal RPE depigmentation).
The American Academy of Ophthalmology (AAO) revised its guidelines in 2016 to decrease the maximum dosage from 6.5 mg/kg/day to 5 mg/kg/day to minimize retinal toxicity.
Melles and Marmor 2014 study demonstrated that patients whose dose exceeded 5 mg/kg per day had a 10% cumulative risk of developing retinopathy within 10 years (rising to 40% after 20 years).
By comparison, patients on a lower dose of 4 - 5 mg/kg/day had a cumulative risk of 2% within 10 years and 20% risk after 20 years.
Please note the 2014 study was performed only in adult patients and doses must continue to be adjusted for renal insufficiency.
Whilst retinal toxicity from HCQ therapy cannot be completely prevented, effective screening can help recognize patients before significant risk of central vision loss occurs.
Current recommendations suggest that patients prescribed HCQ should undergo a baseline ophthalmic examination when therapy starts. This includes:
- Fundus examination to exclude pre-existing retinal or optic nerve damage;
- Central 10-2 visual field testing (central 10-2 for non-Asian patients and central 24-2 or 30-2 for Asian patients);
- Spectral-domain optical coherence tomography (if suspicion of pre-existing macular disease or optic neuropathy).
Please note that a daily dose that exceeds 5 mg is only one risk factor for Plaquenil related retinotoxicity. Other risk factors are:
- Cumulative dose (treatment duration);
- Obesity (BMI>30.0);
- Age over 60 years;
- Renal or hepatic functional impairment;
- Pre-existing retinal disease;
- Concurrent tamoxifen therapy.
The risk of toxicity was found to sharply increase after 5 years, but the majority of cases of retinotoxicity were found in patients with cumulative dose of 1000g (level reached in about 7 years if patient on a dose of 400 mg/day).
The table below summarizes the most common and the less common side effects of Plaquenil:
| Common side effects | Less common side effects |
| Headache | Blurred vision, change in vision, eye pain |
| Itching | Black, tarry stools |
| Nausea or vomiting | Blood in urine or stools |
| Stomach cramps | Convulsions |
| Diarrhea | Fever or chills |
| Skin rash | Cough or hoarseness, sore throat |
| Loss of appetite | Lower back or side pain |
| Drowsiness | Unusual bleeding or bruising |
References
Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmol. 2014; 132(12):1453-60.
Marmor MF, Kellner U, Lai TY, Melles RB, Mieler WF; American Academy of Ophthalmology. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology. 2016; 123(6):1386-94.
Marmor MF, Kellner U, Lai TY, Lyons JS, Mieler WF; American Academy of Ophthalmology. Revised recommendations on screening for chloroquine and hydroxychloroquine retinopathy. Ophthalmology. 2011; 118(2):415-22.
Specialty: Pharmacology
Article By: Denise Nedea
Published On: October 31, 2020 · 12:00 AM
Last Checked: October 31, 2020
Next Review: October 31, 2025