Hydroxychloroquine Sulfate Tablets, USP
Hydroxychloroquine sulfate, USP is a colorless crystalline solid, soluble in water to at least 20 percent; chemically the drug is (±)-2-[[4-[(7-Chloro-4-quinolyl)amino]pentyl]ethylamino] ethanol sulfate (1:1) (salt).
Molecular formula: C18H26ClN3O•H2SO4
Molecular Weight: 433.95
Hydroxychloroquine sulfate tablets, USP contain 200 mg hydroxychloroquine sulfate, equivalent to 155 mg base, and are for oral administration.
Inactive Ingredients: colloidal silicon dioxide, dextrates, hypromellose, magnesium stearate, maltodextrin, microcrystalline cellulose, polydextrose, polyethylene glycol, sodium starch glycolate, starch (corn), titanium dioxide, and triacetin.
Mechanism of action
Malaria: The precise mechanism by which hydroxychloroquine exhibits activity against Plasmodium is not known. Hydroxychloroquine, like chloroquine, is a weak base and may exert its effect by concentrating in the acid vesicles of the parasite and by inhibiting polymerization of heme. It can also inhibit certain enzymes by its interaction with DNA.
Activity in vitro and in Clinical Infections: Hydroxychloroquine is active against the erythrocytic forms of chloroquine sensitive strains of Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax. Hydroxychloroquine is not active against the gametocytes and exoerythrocytic forms including the hypnozoite stage (P. vivax and P. ovale) of the Plasmodium parasites.
P. falciparum strains exhibiting reduced susceptibility to chloroquine also show reduced susceptibility to hydroxychloroquine.
Resistance of Plasmodium parasites to chloroquine is widespread.
Patients in whom chloroquine or hydroxychloroquine have failed to prevent or cure clinical malaria or parasitemia, or patients who acquired malaria in a geographic area where chloroquine resistance is known to occur should be treated with another form of antimalarial therapy.
Rheumatoid Arthritis and Systemic Lupus Erythematosus: The mechanisms underlying the anti-inflammatory and immunomodulatory effects of hydroxychloroquine sulfate are unknown.
INDICATIONS AND USAGE
Malaria: Hydroxychloroquine sulfate is indicated for the treatment of uncomplicated malaria due to P. falciparum, P. malariae, P. ovale, and P. vivax.
Hydroxychloroquine sulfate is indicated for the prophylaxis of malaria in geographic areas where chloroquine resistance is not reported.
Limitations of Use in Malaria
- Hydroxychloroquine sulfate is not recommended for the treatment of complicated malaria.
- Hydroxychloroquine sulfate is not effective against chloroquine or hydroxychloroquine-resistant strains of Plasmodium species.
Hydroxychloroquine sulfate is not recommended for the treatment of malaria acquired in geographic areas where chloroquine resistance occurs or when the Plasmodium species has not been identified.
- Hydroxychloroquine sulfate is not recommended for malaria prophylaxis in geographic areas where chloroquine resistance occurs.
- Hydroxychloroquine sulfate does not prevent relapses of P. vivax or P. ovale because it is not active against the hypnozoite forms of these parasites. For radical cure of P. vivax and P. ovale infections, concomitant therapy with an 8-aminoquinoline compound is necessary.
Prior to prescribing hydroxychloroquine sulfate for the treatment or prophylaxis of malaria, consult the Centers for Disease Control and Prevention (CDC) Malaria website (http://www.cdc.gov/malaria).
Lupus Erythematosus: Hydroxychloroquine sulfate is indicated for the treatment of chronic discoid lupus erythematosus and systemic lupus erythematosus in adults.
Rheumatoid Arthritis: Hydroxychloroquine sulfate is indicated for the treatment of acute and chronic rheumatoid arthritis in adults.
Use of hydroxychloroquine sulfate is contraindicated in patients with known hypersensitivity to 4aminoquinoline compounds.
Resistant strains of malaria: Hydroxychloroquine sulfate is not effective against chloroquine-resistant strains of P. falciparum.
Ocular: Irreversible retinal damage has been observed in some patients who had received hydroxychloroquine sulfate. Significant risk factors for retinal damage include daily doses of hydroxychloroquine sulfate greater than 6.5 mg/kg (5 mg/kg base) of actual body weight, durations of use greater than five years, subnormal glomerular filtration, use of some concomitant drug products such as tamoxifen citrate and concurrent macular disease.
A baseline ocular examination is recommended within the first year of starting hydroxychloroquine sulfate. The baseline exam should include: best corrected distance visual acuity (BCVA), an automated threshold visual field (VF) of the central 10 degrees (with retesting if an abnormality is noted), and spectral domain ocular coherence tomography (SD-OCT).
Cardiac Effects, including Cardiomyopathy and QT prolongation: Postmarketing cases of life-threatening and fatal cardiomyopathy have been reported with use of hydroxychloroquine sulfate as well as with use of chloroquine. Patients may present with atrioventricular block, pulmonary hypertension, sick sinus syndrome or with cardiac complications. ECG findings may include atrioventricular, right or left bundle branch block. Signs or symptoms of cardiac compromise have appeared during acute and chronic treatment. Clinical monitoring for signs and symptoms of cardiomyopathy is advised, including use of appropriate diagnostic tools such as ECG to monitor patients for cardiomyopathy during hydroxychloroquine sulfate therapy.
Worsening of psoriasis and porphyria: Use of hydroxychloroquine sulfate in patients with psoriasis may precipitate a severe attack of psoriasis. When used in patients with porphyria the condition may be exacerbated. The preparation should not be used in these conditions unless in the judgment of the physician the benefit to the patient outweighs the possible hazard.
Proximal Myopathy and Neuropathy: Skeletal muscle myopathy or neuropathy leading to progressive weakness and atrophy of proximal muscle groups, depressed tendon reflexes, and abnormal nerve conduction, have been reported. Muscle and nerve biopsies have been associated with curvilinear bodies and muscle fiber atrophy with vacuolar changes. Assess muscle strength and deep tendon reflexes periodically in patients on long-term therapy with hydroxychloroquine sulfate.
Neuropsychiatric events, including suicidality: Suicidal behavior has been rarely reported in patients treated with hydroxychloroquine sulfate.
Hypoglycemia: Hydroxychloroquine sulfate has been shown to cause severe hypoglycemia including loss of consciousness that could be life threatening in patients treated with or without antidiabetic medications. Patients treated with hydroxychloroquine sulfate should be warned about the risk of hypoglycemia and the associated clinical signs and symptoms. Patients presenting with clinical symptoms suggestive of hypoglycemia during treatment with hydroxychloroquine sulfate should have their blood glucose checked and treatment reviewed as necessary.
General: Use with caution in patients with gastrointestinal, neurological, or blood disorders, and in those with a sensitivity to quinine.
Hepatic/Renal Disease: Antimalarial compounds should be used with caution in patients with hepatic disease or alcoholism or in conjunction with known hepatotoxic drugs. A reduction in dosage may be necessary in patients with hepatic or renal disease, as well as in those taking medicines known to affect these organs.
Hematologic Effects/Laboratory Tests: Antimalarial compounds should be used with caution in patients with hepatic disease or alcoholism or in conjunction with known hepatotoxic drugs. Periodic blood cell counts should be performed if patients are given prolonged therapy. If any severe blood disorder such as aplastic anemia, agranulocytosis, leukopenia, or thrombocytopenia, appears which is not attributable to the disease under treatment, consider discontinuation of hydroxychloroquine sulfate.
Hydroxychloroquine sulfate should be administered with caution in patients having glucose-6-phosphate dehydrogenase (G-6-PD) deficiency.
Dermatologic Effects: Dermatologic reactions to hydroxychloroquine sulfate may occur and, therefore, proper care should be exercised when it is administered to any patient receiving a drug with a significant tendency to produce dermatitis.
Digoxin: Concomitant hydroxychloroquine sulfate and digoxin therapy may result in increased serum digoxin levels: serum digoxin levels should be closely monitored in patients receiving combined therapy.
Insulin or antidiabetic drugs: As hydroxychloroquine sulfate may enhance the effects of a hypoglycemic treatment, a decrease in doses of insulin or antidiabetic drugs may be required.
Drugs that prolong QT interval and other arrhythmogenic drugs: Hydroxychloroquine sulfate prolongs the QT interval and should not be administered with other drugs that have the potential to induce cardiac arrhythmias. Also, there may be an increased risk of inducing ventricular arrhythmias if hydroxychloroquine sulfate is used concomitantly with other arrhythmogenic drugs.
Mefloquine and other drugs known to lower the convulsive threshold: Hydroxychloroquine sulfate can lower the convulsive threshold. Coadministration of hydroxychloroquine sulfate with other antimalarials known to lower the convulsion threshold (e.g., mefloquine) may increase the risk of convulsions.
Antiepileptics: The activity of antiepileptic drugs might be impaired if coadministered with hydroxychloroquine sulfate.
Methotrexate: Combined use of methotrexate with hydroxychloroquine sulfate has not been studied and may increase the incidence of adverse effects.
Cyclosporin: An increased plasma cyclosporin level was reported when cyclosporin and hydroxychloroquine sulfate were coadministered.
The following interactions have been observed on treatment with the structurally related substance chloroquine phosphate, and therefore cannot be ruled out for hydroxychloroquine.
Praziquantel: Chloroquine has been reported to reduce the bioavailability of praziquantel.
Antacids and kaolin: Antacids and kaolin can reduce absorption of chloroquine; an interval of at least 4 hours between intake of these agents and chloroquine should be observed.
Cimetidine: Cimetidine can inhibit the metabolism of chloroquine, increasing its plasma level. Concomitant use of cimetidine should be avoided.
Ampicillin: In a study of healthy volunteers, chloroquine significantly reduced the bioavailability of ampicillin.
Use in specific populations
Teratogenic Effects: Human pregnancies resulting in live births have been reported in the literature and no increase in the rate of birth defects has been demonstrated. Embryonic deaths and malformations of anophthalmia and microphthalmia in the offspring have been reported when pregnant rats received large doses of chloroquine.
Nursing Mothers: Caution should be exercised when administering hydroxychloroquine sulfate to nursing women. It has been demonstrated that hydroxychloroquine administered to nursing women is excreted in human milk and it is known that infants are extremely sensitive to the toxic effects of 4aminoquinolines.
Pediatric Use: Safety and efficacy have not been established in the chronic use of hydroxychloroquine sulfate for systemic lupus erythematosus and juvenile idiopathic arthritis in children. Children are especially sensitive to the 4-aminoquinoline compounds. Most reported fatalities followed the accidental ingestion of chloroquine, sometimes in small doses (0.75 g or 1 g in one 3-year-old child). Patients should be strongly warned to keep these drugs out of the reach of children.
Geriatric Use: Clinical studies of hydroxychloroquine sulfate did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. However, this drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function.
The 4-aminoquinoline compounds are very rapidly and completely absorbed after ingestion, and in accidental overdosage, or rarely with lower doses in hypersensitive patients, toxic symptoms may occur within 30 minutes. The symptoms of overdosage may include headache, drowsiness, visual disturbances, cardiovascular collapse, convulsions, hypokalemia, rhythm and conduction disorders including QT prolongation, torsades de pointes, ventricular tachycardia and ventricular fibrillation, followed by sudden potentially fatal respiratory and cardiac arrest. Treatment is symptomatic and must be prompt. Immediate gastric lavage until the stomach is completely emptied is indicated. After lavage, activated charcoal is introduced by the stomach tube within 30 minutes of ingestion of the drug may inhibit further intestinal absorption. To be effective, the dose of activated charcoal should be at least five times the estimated dose of hydroxychloroquine ingested.
Consideration should be given to administering diazepam parenterally since studies suggest that it may be beneficial in reversing chloroquine and hydroxychloroquine cardiotoxicity.
Respiratory support and shock management should be instituted as necessary.
Exchange transfusions are used to reduce the level of 4-aminoquinoline drug in the blood.
A patient who survives the acute phase and is asymptomatic should be closely observed for at least six hours. Fluids may be forced and sufficient ammonium chloride (8 g daily in divided doses for adults) may be administered for a few days to acidify the urine. This will promote urinary excretion in cases of both overdosage and sensitivity. However, caution must be exercised in patients with impaired renal function and/or metabolic acidosis.
DOSAGE AND ADMINISTRATION
One hydroxychloroquine sulfate tablet contains 200 mg of hydroxychloroquine sulfate, which is equivalent to 155 mg base.
Take hydroxychloroquine sulfate tablets with a meal or a glass of milk.
Adults: 400 mg (310 mg base) once weekly on the same day of each week starting 2 weeks prior to exposure, and continued for 4 weeks after leaving the endemic area.
Weight-based dosing in adults and pediatric patients: 6.5 mg/kg (5 mg/kg base), not to exceed 400 mg (310 mg base), once weekly on the same day of the week starting 2 weeks prior to exposure, and continued for 4 weeks after leaving the endemic area.
Treatment of Uncomplicated Malaria
Adults: 800 mg (620 mg base) followed by 400 mg (310 mg base) at 6 hours, 24 hours and 48 hours after the initial dose (total 2000 mg hydroxychloroquine sulfate or 1550 mg base).
Weight based dosage in adults and pediatric patients: 13 mg/kg (10 mg/kg base), not to exceed 800 mg (620 mg base) followed by 6.5 mg/kg (5 mg/kg base), not to exceed 400 mg (310 mg base), at 6 hours, 24 hours and 48 hours after the initial dose. Hydroxychloroquine sulfate film-coated tablets cannot be divided, therefore they should not be used to treat patients who weigh less than 31 kg.
For radical cure of P. vivax and P. malariae infections, concomitant therapy with an 8-aminoquinoline compound is necessary.
Lupus Erythematosus: The recommended adult dosage is 200 to 400 mg (155 to 310 mg base) daily, administered as a single daily dose or in two divided doses. Doses above 400 mg a day are not recommended.
The incidence of retinopathy has been reported to be higher when this maintenance dose is exceeded.
Rheumatoid Arthritis: The action of hydroxychloroquine is cumulative and may require weeks to months to achieve the maximum therapeutic effect.
Initial adult dosage: 400 mg to 600 mg (310 to 465 mg base) daily, administered as a single daily dose or in two divided doses. In a small percentage of patients, side effects may require temporary reduction of the initial dosage.
Maintenance adult dosage: When a good response is obtained, the dosage may be reduced by 50 percent and continued at a maintenance level of 200 mg to 400 mg (155 to 310 mg base) daily, administered as a single daily dose or in two divided doses.
Do not exceed 600 mg or 6.5 mg/kg (5 mg/kg base) per day, whichever is lower, as the incidence of retinopathy has been reported to be higher when this maintenance dose is exceeded.
Corticosteroids and salicylates may be used in conjunction with hydroxychloroquine sulfate, and they can generally be decreased gradually in dosage or eliminated after a maintenance dose of hydroxychloroquine sulfate has been achieved.