Drug Interaction Report

Medications containing local anesthetics such as procaine penicillin may cause methemoglobinemia, a rare condition that can lead to oxygen deprivation in tissues and vital organs due to reduced oxygen-carrying capacity of the blood. The risk is increased when combined with other medications that can also induce methemoglobinemia such as chloroquine. Individuals may be more susceptible to developing methemoglobinemia during treatment with these medications if they are very young (especially neonates and infants) or have diseases of the heart or lungs, certain genetic predispositions, or glucose-6-phosphate dehydrogenase deficiency. Close medical supervision is necessary when medications that can cause methemoglobinemia are used together. Signs and symptoms of methemoglobinemia may occur immediately or hours after treatment. Patients or their caregivers should seek immediate medical attention if they develop gray discoloration of the skin, abnormal blood coloration, nausea, headache, dizziness, lightheadedness, fatigue, shortness of breath, rapid or shallow breathing, a rapid heartbeat, palpitation, anxiety, or confusion. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

You may want to limit your consumption of grapefruit or grapefruit juice during treatment with chloroquine. Grapefruit juice can significantly increase the blood levels and effects of chloroquine, which may result in an irregular heart rate or other conduction disturbances. Hydroxychloroquine should also be taken with food or milk to reduce the incidence of stomach upset. Talk to your doctor if you have any questions or concerns. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with chloroquine. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.