Primaquine Phosphate 26.3mg Tabs

Primaquine is an 8-aminoquinoline antimalarial. Its exact mechanism is not fully understood but is believed to involve the production of reactive oxygen species (ROS) that interfere with parasite mitochondrial function and electron transport. It is active against the exoerythrocytic (liver) stages of Plasmodium vivax and P. ovale (hypnozoites), preventing relapses. It also has gametocytocidal activity against all Plasmodium species, including P. falciparum, rendering gametocytes non-infectious to mosquitoes, thus helping to reduce transmission.

Urgent Side Effects: Seek Medical Attention Immediately

Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of methemoglobinemia, a rare but potentially deadly condition, including:
+ Blue or gray discoloration of the lips, nails, or skin
+ Abnormal heartbeat
+ Seizures
+ Severe dizziness or fainting
+ Severe headache
+ Excessive sleepiness
+ Feeling tired or weak
+ Shortness of breath
Other severe side effects, such as:
+ Extreme fatigue or weakness
+ Dark urine or yellowing of the skin and eyes (jaundice)
+ Fever, chills, or sore throat
+ Dizziness
+ Abnormal heartbeat (prolonged QT interval), which can cause:
- Fast heartbeat
- Abnormal heartbeat
- Fainting

Other Possible Side Effects

Most people taking this medication do not experience severe side effects. However, some may occur. If you experience any of the following side effects, contact your doctor or seek medical help if they bother you or do not go away:

Stomach pain or cramps
* Upset stomach or vomiting

Reporting Side Effects

This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced, including any symptoms.
If you have been diagnosed with lupus or rheumatoid arthritis.
If you have glucose-6-phosphate dehydrogenase (G6PD) deficiency or if you have not undergone testing for this condition.
If you are currently taking or have recently taken quinacrine.
If you are taking any medications that may affect your bone marrow's ability to produce necessary cells. There are numerous medications that can have this effect, so consult your doctor or pharmacist if you are unsure.
If you are pregnant or think you may be pregnant. Do not take this medication if you are pregnant.
* If you are breastfeeding or plan to breastfeed.

This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. Verify that it is safe to take this medication with all your other medications and health conditions before starting treatment. Never start, stop, or adjust the dosage of any medication without consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood work and laboratory tests should be conducted as directed by your doctor to monitor your condition.

To minimize the risk of severe side effects, adhere strictly to the dosage and administration schedule prescribed by your doctor. Do not exceed the recommended dose, and do not take the medication more frequently or for a longer duration than instructed.

This medication may pose a risk to an unborn baby. Therefore, a pregnancy test will be conducted before initiating treatment to confirm that you are not pregnant. If you are of childbearing potential, it is crucial to use effective birth control methods while taking this medication. Continue using birth control after your last dose until after your next menstrual period to prevent pregnancy.

If you become pregnant or suspect you may be pregnant, notify your doctor immediately. Additionally, if your sexual partner may become pregnant, use a condom consistently while taking this medication and for 3 months after your last dose. If your partner becomes pregnant, contact the doctor right away to discuss the potential risks and necessary precautions.

• Patients with G6PD deficiency (risk of hemolytic anemia)
• Patients with severe systemic diseases (e.g., rheumatoid arthritis, lupus erythematosus) due to risk of myelosuppression
• Concomitant use with other drugs that may cause hemolysis or myelosuppression (e.g., quinacrine, certain sulfonamides)
• Pregnancy (unless benefits outweigh risks and G6PD status of fetus is known and normal)
• Breastfeeding (if infant is G6PD deficient or status unknown)

• Quinacrine (increases primaquine toxicity, contraindicated)
• Drugs that inhibit CYP2D6 (e.g., bupropion, fluoxetine, paroxetine, quinidine, ritonavir, duloxetine, amiodarone, cimetidine, clomipramine, haloperidol, metoclopramide, propafenone, thioridazine, venlafaxine): May increase primaquine levels and risk of adverse effects, including hemolysis.
• Drugs that cause myelosuppression (e.g., antineoplastics, chloramphenicol): Increased risk of hematologic toxicity.

• Drugs that induce CYP2D6 (e.g., rifampin): May decrease primaquine levels, potentially reducing efficacy.
• Other antimalarials: Potential for additive adverse effects or altered efficacy.

• Not specifically identified as minor, but general caution with drugs affecting liver enzymes or hematopoiesis.

• Darkening of urine (hemolysis)
• Yellowing of skin or eyes (jaundice)
• Unusual tiredness or weakness (anemia)
• Shortness of breath
• Bluish discoloration of lips or fingernails (cyanosis, methemoglobinemia)
• Abdominal cramps
• Nausea
• Vomiting

Generally avoided. Primaquine is a Category C drug. It can cross the placenta and cause hemolytic anemia in a G6PD deficient fetus. Use only if the potential benefit justifies the potential risk to the fetus, and only if the G6PD status of the fetus is known and normal.

Contraindicated if the infant is G6PD deficient or if the infant's G6PD status is unknown, due to the risk of hemolytic anemia in the infant. If the infant is known to be G6PD normal, use with caution and monitor the infant for signs of hemolysis.

Contraindicated in infants less than 6 months of age due to the immaturity of their G6PD enzyme system and higher risk of hemolysis. For children ≥ 6 months, G6PD testing is mandatory. Dosing is weight-based. Close monitoring for hemolysis is crucial.

Use with caution. Elderly patients may have reduced renal or hepatic function, which could alter primaquine pharmacokinetics. Monitor for adverse effects, especially hematologic toxicity.

• Always perform G6PD deficiency testing before initiating primaquine therapy. This is the most critical safety step.
• Primaquine is the only drug effective against the hypnozoite (liver) stage of *P. vivax* and *P. ovale*, preventing relapses.
• It is also crucial for *P. falciparum* malaria control due to its gametocytocidal activity, reducing transmission.
• Administer with food to minimize gastrointestinal upset.
• Educate patients on signs of hemolysis (dark urine, jaundice, fatigue) and methemoglobinemia (cyanosis) and to seek immediate medical attention if these occur.
• The 14-day course for radical cure must be completed, even if symptoms resolve, to prevent relapse.
• In areas where G6PD testing is not immediately available, the risks of not treating *P. vivax* relapse must be weighed against the risk of hemolysis, but this is generally not recommended without testing.

• Tafenoquine: Another 8-aminoquinoline with activity against hypnozoites and gametocytes, also requires G6PD testing. Approved for radical cure of *P. vivax* and prophylaxis.
• For *P. falciparum* gametocytocidal activity, artemisinin-based combination therapies (ACTs) also have some gametocytocidal effect, but primaquine is more potent for this purpose.

If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.