Krintafel (Tafenoquine) - Oral

What Is Krintafel?

Krintafel (tafenoquine) is a pill taken by mouth to treat and prevent the relapse of Plasmodium vivax malaria, which is an infection caused by parasites that mosquitoes carry. Plasmodium vivax is the name of the parasite that almost always causes malaria.

After acute malaria infections, this parasite can lie dormant (inactive and not causing symptoms) in your liver, then cause later relapses of malaria. This means you can experience more malaria episodes without being bitten again by a mosquito. Krintafel prevents these relapses.

Krintafel works against the parasite within your liver by disturbing certain processes required to grow. It is an add-on medication and must be taken with another antimalarial drug called chloroquine.

The generic name for Krintafel is tafenoquine, but it is only available as a brand name product. It’s also a prescription drug, so you can’t purchase it over-the-counter (OTC). You will need a prescription from a healthcare provider.

What Is Krintafel Used For?

Krintafel is used in people aged 16 or older in addition to another antimalarial drug to treat and prevent the malaria relapse, a parasitic infection most often transmitted by mosquitoes.

The disease is rare in the United States (U.S.), but unfortunately much more common in other areas of the world. Most cases in the U.S. come from travelers who have visited tropical areas like Africa, South and Southeast Asia, and parts of South and Central America and the Caribbean.

The "classic" sign of infection is malaria paroxysm, the cycling of cold symptoms (chills and shivering) with hot symptoms (sweating and fever) every few hours.

Some of the most common early symptoms of malaria include:

• Headache
• Fever
• Fatigue
• Dry cough
• Nausea
• Vomiting

More severe cases of malaria can cause:

• Acute breathing problems
• Changes in consciousness
• Jaundice (yellowing of the skin and eyes)
• Shock
• Coma
  

How to Take Krintafel

Take Krintafel exactly as your healthcare provider tells you to. You will take this medication along with another antimalarial drug, chloroquine.

You will most likely take Krintafel as a single dose on the first or second day you start taking chloroquine. Swallow the tablets whole. Do not break, crush, or chew them.

Take Krintafel with food to increase how much of the drug gets absorbed into your system. Ideally, this would be with a meal that includes plenty of fat. Studies showed higher absorption rates in people who ate around 1,000 calories, at least 60% of them from fat. This may sound like a burden, but remember, Krintafel is usually just taken once as a single dose.

If you vomit within one hour after taking your dose of Krintafel, you should repeat the dose. If the same thing happens again, don’t attempt another dose. Consult your healthcare provider.

Storing Krintafel

Store Krintafel at room temperature (between 68 F and 77 F) in the original package, out of reach of children and pets. Avoid storing it in an area with a lot of heat and moisture, like the bathroom.

What Are the Side Effects of Krintafel?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

The following are some of the more common side effects of using Krintafel. If you notice these side effects and think they are severe or if they do not go away, you should notify your healthcare provider:

• Dizziness
• Nausea
• Vomiting
• Decreased hemoglobin (a protein in your red blood cells that delivers oxygen to your organs)
• Headache
  

Severe Side Effects

Call your healthcare provider immediately if you feel you are experiencing severe side effects such as any of the following. Call 911 if your symptoms feel life-threatening or think you’re having a medical emergency.

Severe side effects and their symptoms include:

• Methemoglobinemia is rare but has been associated with taking Krintafel. It is a blood disorder that makes some of your red blood cells unable to carry oxygen, resulting in symptoms like cyanosis, weakness, shortness of breath, heart rhythm problems, or impaired thinking in severe cases.
• Psychiatric symptoms such as anxiety, insomnia, or abnormal dreams may occur, potentially more so in individuals with a history of psychiatric problems.
• Hypersensitivity reactions such as urticaria and angioedema (hives and swelling) are possible when taking Krintafel. Be aware of signs and symptoms, including dizziness, rash, upset stomach, or patchy welts on your skin. Seek help as soon as possible if you experience these symptoms.
  

Long-Term Side Effects

No specific long-term side effects apart from the possible ones listed above are of concern, as Krintafel is typically taken once as a single dose.

Dosage: How Much Krintafel Should I Take?

Modifications

In some cases, you may need to adjust your treatment with Krintafel or use an alternative medication.

History of Psychiatric Disorders

Having any kind of psychiatric history doesn’t automatically rule out Krintafel as a treatment option, but you should have a conversation with your healthcare provider about the benefit of taking it given the potential risk for adverse psychiatric reactions. Note that these reactions could be delayed in onset given the fact that Krintafel remains in your system for several weeks.

Pregnancy

Taking Krintafel while pregnant is not recommended. The effect the drug has on the fetus is not well understood and may be harmful. This is especially true if the fetus has G6PD deficiency, a genetic enzyme deficiency that may cause serious blood problems if exposed to certain medications such as Krintafel.

Nursing

If your infant has G6PD deficiency, or if you don’t know the G6PD status of your baby, don’t breastfeed for three months after you take Krintafel.

Children

The safety and effectiveness of Krintafel has not been established in children younger than 16. Therefore, this medication is not approved for use in this population.

Older Age

Studies specifically evaluating Krintafel use in people older than 65 have not been done, but clinical experience hasn’t suggested that older individuals respond differently to Krintafel compared with younger adults. No dosage changes are necessary.

Missed Dose

Krintafel is taken one time as a single dose, so there’s no need to worry about missing any doses. Your healthcare provider will let you know when to take your Krintafel dose in relation to your other antimalarial medication.

Overdose: What Happens If I Take Too Much Krintafel?

Since Krintafel is taken just one time as a single dose, you don’t need to be concerned about overdosing.

If for some reason, you do end up with too much Krintafel in your system, symptoms may include low hemoglobin levels and potentially methemoglobinemia, in which case you should notify your healthcare provider as soon as possible.

Precautions

What Are Reasons I Shouldn't Take Krintafel?

You shouldn’t take Krintafel if any of the following apply to you:

• G6PD deficiency: You should let your healthcare provider know before using Krintafel if you have a genetic disorder called G6PD deficiency. If you don’t know whether you have this deficiency, your healthcare provider should test you before prescribing Krintafel. Using Krintafel with this disorder can cause dangerous changes in red blood cell counts (anemia) as well as clotting and bleeding problems.
• A history of severe psychiatric disorders: Have a conversation with your healthcare provider about whether you should take Krintafel.
• If you are pregnant: Taking Krintafel while pregnant isn’t recommended since the effect the drug has on the fetus isn’t well understood and may be harmful, especially if the fetus has G6PD deficiency.
  

What Other Medications Interact With Krintafel?

Taking Krintafel with certain drugs that are metabolized by the proteins organic cation transporter-2 (OCT2) and multidrug and toxin extrusion (MATE) may increase the concentrations of those drugs in your body, potentially making the effects of those drugs stronger.

A few examples of OCT2 substrates include:

• Chantix (varenicline)
• Glucophage (metformin)
• Mirapex (pramipexole)
• Myrbetriq (mirabegron)
• Tikosyn (dofetilide)
• Tradjenta (linagliptin)
• Zantac (ranitidine)

And some MATE substrates:

• Corgard (nadolol)
• Tambocor (flecainide)
• Fluoroquinolone antibiotics including Cipro (ciprofloxacin) and Levaquin (levofloxacin)

Additionally, taking Krintafel with antimalarials other than chloroquine can increase the risk of P. vivax malaria recurrence.

Ensure the healthcare provider prescribing Krintafel for you is aware of your complete medication list. They may have you take a break from some of these medications or temporarily decrease the dose of them while Krintafel is in your system.

What Medications Are Similar to Krintafel?

Krintafel is used to target the dormant form of the malaria parasite, to prevent relapses of the infection. It is taken in addition to other antimalarial drugs that target the active form of the malaria parasite. Some examples of other antimalarial drugs are:

• Arakoda, which is the same drug as Krintafel, but taken to prevent (prophylaxis) malaria
• Chloroquine
• Plaquenil (hydroxychloroquine)
• Qualaquin (quinine)
• Primaquine
• Mefloquine
• Malarone (atovaquone/proguanil)

You may take one or some of these drugs along with Krintafel. Ask your healthcare provider if you have questions.

How Can I Stay Healthy While Taking Krintafel?

Malaria is rare in the United States. Only a couple thousand infections are diagnosed per year, and the vast majority is in travelers returning from tropical areas where transmission is high. If you are planning to travel to a tropical area where exposure to malaria is possible or likely, it is essential to take proper precautions like packing and using plenty of insect repellant, taking prophylactic medications, and potentially receiving a vaccine.

You can use the CDC Yellow Book to see recommendations for the country or countries you’ll be visiting, and even see where there is the highest risk of malaria. Speak with your healthcare provider to get everything you need before you leave.

If you feel you have symptoms of an infection and you have recently traveled, do not ignore the signs. Promptly see a healthcare provider. When left untreated, malaria can progress to much more severe infections. Treatment should be initiated as soon as possible, and adherence to your medications is essential. Treatment with the right drugs against the right parasite can clear the infection from your body.

In addition to treating malaria with prescription drugs, you can support good health by making sure you are staying hydrated, maintaining adequate nutrition with a proper diet, getting enough rest, and staying at comfortable temperatures. You can also use over-the-counter pain and fever medications if approved and directed by your healthcare provider.