Thread by @aishaikh

💥 Hydroxychloroquine - is an
Anti-malarial drug that also has immunomodulatory properties
⚡️It is used to Rx auto-immune conditions
⚡️The origin and history of this drug is as fascinating as it’s benefits
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@RenalFellowNtwk
#Lupus
#medtwitter

💥 Quinine was 1st found in the bark of the ‘Cinchona’ tree by the Inca in Peru to Rx ‘shivering’
⚡️It is believed that the tree got its name ‘Cinchona’ after it was used to treat the ‘Countess of Chinchon’ for a febrile illness in the 1630s
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💥 In the early days, the Cinchona bark tree powder was called the ‘Jesuits Powder’ (and not Quinine)
⚡️However, this 👆🏽is why side effects from quinine - such as tinnitus, headaches and poor vision are referred to as ‘Cinchonism’
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💥 By the 1650’s, the ‘Jesuits Powder’ was being use to Rx ‘intermittent fevers’
⚡️Recall that malaria can cause relapsing fevers (intermittent): 3-day & 4-day fever cycles called tertian & quartan respectively (caused by different plasmodia species)
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💥’Jesuits Powder’ was also used in Rome in the mid-17th century as Malaria was endemic in Rome
⚡️In fact, the word ‘Malaria’ comes from the medieval Italian words means ‘Mal’ & ‘Aria’ meaning ‘Bad Air’
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💥It took another 200 years to discover that Malaria was not caused by ‘bad air’ but by parasites!
⚡️This discovery was made by the French Physician Charles Laveran in 1880 for which he received a Nobel Prize in 1907
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💥Even though the ‘Cinchona’ tree bark powder was being used as a medicine for several years, Quinine was not purified from it till 1820
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💥Chloroquine is synthetic form of Quinine
⚡️In the Second World War millions of soldiers received anti-malarial prophylaxis, as malaria was a leading cause of death among soldiers
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💥 During this time it was observed that the anti-malarial drug improved the soldier’s rash & arthritis
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💥 Hydroxychloroquine is a synthetic form of Quinine
⚡️ Hydroxychloroquine was introduced in 1955 & it differs from Chloroquine by a hydroxyl group - this ⬇️ it’s toxicity while conserving it’s efficacy
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💥 HCQ has immunomodulatory properties & is used to treat conditions like Lupus and Rheumatoid arthritis
⚡️Exact mechanism is unclear👇🏽
⚡️It likely inhibits Toll-like receptors, cytokine production, auto-antigen presentation 👇🏽
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💥HCQ is effective in Rx of Lupus especially when there is skin & joint involvement
⚡️There is evidence that it is beneficial in Rx of lupus nephritis when used in combination with immunosuppressive therapy (Attention: Nephrologists‼️)
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💥 It is also important to note that Hydroxychloroquine administration to women with lupus during pregnancy is safe
⚡️It has been shown to ⬇️ risk of premature birth, IUGR & anti-Ro antibodies related cardiac complications (Attention: Nephrologists‼️) 👇🏽
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💥Hydroxychloroquine has also been used in conditions besides Lupus & Rheumatoid Arthritis 👇🏽
⚡️Interestingly, a recent single center RCT showed ⬇️ in proteinuria in patients with IgA Nephropathy (though small number of pts. & short follow up) 👇🏽
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💥Hydroxychloroquine is generally a safe drug but certain adverse effects can occur 👀👇🏽
Of these let’s discuss:
⚡️Retinal toxicity & Skin hyperpigmentation
⚡️These can occur independently, but high cumulative exposure is a risk factor for both
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💥Retinal toxicity
⚡️Exact mechanism is unclear but it is thought to be due to binding of HCQ to melanin in the retinal pigment epithelium
⚡️This can damage photoreceptors & cause vision loss
⚡️Prevention is the 🔑 and hence screening is recommended 👇🏽
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💥 ‘Bulls Eye Maculopathy’ is an advanced disease & at this stage the symptoms are generally irreversible
⚡️It is characterized by a central patchy area of depigmentation of the macula surrounded by a concentric ring of pigmentation
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💥Skin hyperpigmentation can be seen with HCQ👇🏽
Other cutaneous manifestations include:
⚡️Rash
⚡️Easy bruising
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💥Hydroxychloroquine is a relatively safe antimalarial drug & is used to Rx autoimmune conditions like Lupus & Rheumatoid arthritis
⚡️Adverse effects are rare, but Nephrologists, Rheumatologists & Internists should be aware of its toxicities 👆🏽
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