Plaquenil (Hydroxychloroquine): Uses, Dosage, Side Effects, Precautions

Plaquenil (hydroxychloroquine) is classified as a disease-modifying anti-rheumatic drug (DMARD) and antimalarial drug. It comes in pill form and is taken by mouth for rheumatoid arthritis and other conditions. Its method of action isn't fully understood, but it's believed to involve modulating (but not suppressing) the immune system.

Another brand name containing the same active ingredient is Quineprox, and generic forms of hydroxychloroquine are also available.

Uses

Plaquenil is approved by the U.S. Food and Drug Administration (FDA) for treating:

• Rheumatoid arthritis (RA)
• Discoid and systemic lupus erythematosis
• Acute attacks of malaria

For RA and lupus, Plaquenil is prescribed as a disease-modifier, meaning that it:

• Decreases pain
• Lessens inflammation
• Prevents joint damage
• Helps retain physical ability

While it's not known exactly how Plaquenil works, researchers believe it interferes with communication between cells within the immune system. Ultimately, it is thought to block actions that contribute to inflammation.

Plaquenil is a slow-acting drug. Most people who take it begin to notice improvement after one or two months, but it may take up to six months to see the full benefits.

Off-Label Uses

In addition to its benefits as a DMARD and antimalarial, Plaquenil has been found to:

• Improve lipid profiles
• Control glucose and reduce the risk of diabetes mellitus
• Lower the risk of thrombosis in certain at-risk people
• Treat porphyria cutanea tarda (PCT), which is a rare blood disorder

Healthcare providers may prescribe Plaquenil or generic hydroxychloroquine off-label for these or other uses.

Before Taking

Generally, Plaquenil is a monotherapy (used alone) in cases of lupus that don't include major organ involvement.

It's also used as monotherapy in mild RA. In moderate and severe cases, it may be prescribed alone or in combination with methotrexate, sulfasalazine, or both.

Before prescribing this drug, your healthcare provider may perform tests, such as Vectra DA, to assess the severity of your disease and response to current medications.

Precautions and Contraindications

Before you take Plaquenil or generic hydroxychloroquine, tell your healthcare provider if you've ever had an allergic reaction to this or similar drugs.

Plaquenil and other antimalarial drugs may not be safe for people with:

• Liver disease
• Alcoholism
• Other prescription medications that can cause liver toxicity or drugs that can cause QT prolongation
• Retinal or visual-field changes due to this or similar drugs

Other DMARDs

Other common DMARDs on the market include:

• Arava (leflunomide)
• Rheumatrex, Trexall (methotrexate)
• Azulfidine (sulfasalazine)
• Minocin (minocycline)
• Imuran (azathioprine)
• Cellcept (mycophenolate mofetil)
• Cytoxan (cyclophosphamide)
• Neoral, Sandimmune, Gengraf (cyclosporine)

Dosage

The dosage of Plaquenil is weight-dependent. That means the specific dosage you'll get depends on both your illness and how much you weigh.

For rheumatoid arthritis, the usual starting dose of Plaquenil is 400-600 mg/day once daily or twice a day. When a good response is obtained, the dose is reduced by 50%, and the maintenance dose is 200-400 mg/day once daily or twice a day; not exceeding 600 mg or 6.5 mg/kg (5 mg/kg base) per day, whichever is lower. The incidence of retinopathy has been reported to be higher when this maintenance dose is exceeded.

For lupus, the typical dosage ranges from 200 mg to 400 mg per day, in one or two doses. Doses >500 mg/day are not recommended.

For malaria treatment, dosages range up to 800 mg per day.

All listed dosages are according to the drug manufacturer. Check your prescription and talk to your healthcare provider to make sure you are taking the right dose for you.

How to Take and Store

Plaquenil should always be taken with a meal or a glass of milk to help prevent stomach irritation. Swallow the pills whole with liquid. Do not chew or crush Plaquenil tablets.

Don't take antacids within four hours of taking Plaquenil, as they interfere with how your body absorbs this drug, making it less effective.

If you miss a dose, take Plaquenil as soon as you remember, unless it's nearly time for your next dose. In that case, skip the one you missed.

Taking two doses close together at once could lead to overdose. You may have symptoms of toxicity within 30 minutes, which may include:

• Headache
• Drowsiness
• Visual disturbances
• Convulsions
• Hypoakalemia (low blood potassium levels)
• Cardiovascular collapse
• Irregular heartbeat, possibly followed by sudden respiratory and cardiac arrest, which can be fatal

Store your medication at room temperature, away from excess heat or moisture.

Side Effects

Plaquenil is generally well-tolerated, but side effects are possible.

Common

Common side effects linked to Plaquenil include:

• Headache
• Dizziness
• Nausea
• Diarrhea
• Vomiting
• Loss of appetite
• Abdominal pain
• Skin rash

Let your healthcare provider know if any of these side effects are severe or don't go away.

Taking the medication with food may ease digestive side effects.

Severe

In rare cases, Plaquenil can cause a problem with blood flow in the eyes, leading to a condition called hydroxychloroquine retinopathy.

Side effects of hydroxychloroquine retinopathy include:

• Parts of objects or words appear missing
• Sensitivity to light
• Blurred distance vision
• Seeing flashes or streaks of light

Contact your healthcare provider right away if you experience any of these. If not caught early, the condition is often irreversible and can cause impaired vision or even blindness. If it's caught early and you go off the drug, the problem may be reversible.

The risk of developing this rare problem is higher in people who:

• Have taken high doses of Plaquenil for several years
• Are 60 years or older
• Are obese
• Have significant liver or kidney disease
• Have pre-existing retinal disease, macular disease, or cataracts

Anyone starting Plaquenil treatment should have a baseline eye exam within the first year. If you're considered low-risk, you may not need to be tested for another five years.

Other side effects that warrant immediate medical attention include:

• Difficulty hearing
• Ringing in the ears
• Muscle weakness
• Excessive bleeding or easy bruising
• Lightening or loss of hair
• Changes in mood or mental status
• Irregular heartbeat
• Drowsiness
• Convulsions

Warnings and Interactions

Certain drugs may interact with Plaquenil, affecting how it works or causing it to be less effective. Tell your healthcare provider about every medication and supplement you are taking, be it prescription or over-the-counter.

Drugs that may interact negatively with Plaquenil include:

• Antacids and kaolin
• Ampicillin
• Cimetidine
• Diabetic medications, including insulin
• Codeine
• Anti-seizure drugs
• Heart rhythm drugs and drugs that lengthen the heart's QT interval
• Digoxin
• Albuterol
• Amitriptyline and other tricyclic antidepressants
• Clarithromycin
• Atomoxetine
• Botulinum toxins
• Methotrexate

Pregnancy

If you're pregnant or trying to get pregnant, discuss Plaquenil with your healthcare provider. Though Plaquenil is generally regarded as safe during pregnancy, it's recommended that you use effective birth control while taking the drug and for up to six months after going off of it.