Overview:
Tafenoquine is an antimalarial drug initially developed by a group of scientists from the Walter Reed Army Institute of Research in 1978 as an alternative to Primaquine, an antimalarial drug. The Food and Drug Administration approved the drug for prophylactic use of malaria in the United States and Australia in 2018.
How Does Tafenoquine Work?
The exact mechanism of action of the drug has yet to be completely established. However, various studies explain that the drug has longer and more effective action than its counterparts. It is composed of eight aminoquinoline and completely eliminates the growth of malarial parasites, and broadens its applicability for chemoprophylaxis.
Uses:
Tafenoquine is specifically used to treat patients suffering from malaria diseases. It is effective in individuals over 16 years and is used to prevent disease relapse.
Dosage:
The drug is taken in a single dose of 300 mg once a day. It is available in pink, film-coated capsules. Taking the drug after a meal is safer to increase absorption and improve efficacy. A bottle contains approximately 30 tablets with a child-resistant closure. Use the drug within three months after opening.
Warnings:
The drug can only be administered in adults. Also, pregnant and breastfeeding women should be carefully examined, and only if it is mandatory, the drug prescribed to avoid birth defects and harm to the child.
For Patients
What Is Malaria?
The bite of an infected mosquito causes malaria. It is a parasitic infection. It causes high fever, chills, and flu-like illness. The disease may be fatal if left undiagnosed. Since it affects the blood, avoiding blood transfusion from those individuals is better. It can affect all individuals irrespective of their age. It can also be transferred from the mother to the unborn child. Taking proper treatment and rest can help in the success of the treatment.
Things to Inform the Doctor Before Taking Tafenoquine:
Before starting Tafenoquine, it is safe to inform the doctor regarding any health issues and current medication as it helps them alter the dose accordingly and avoid unnecessary drug interactions. Some of the important things to be mentioned are listed below.
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Inform the doctor if there is any previous history of allergic reaction to the drug or any other drugs and their particles.
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Give a good medical history and family history.
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Inform the list of current medications; it is always better to carry the drugs or the prescription while visiting the doctor.
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In the case of any liver or kidney disease, doctors specifically mention the doctor as most drugs are metabolized in the liver and may precipitate the condition.
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Pregnant women and women planning their pregnancy should inform the doctor as the drug may cause birth defects in children.
How to Take Tafenoquine?
The drug should be taken in proper doses as recommended by the doctor. Drink plenty of water after the drug intake for proper metabolism and elimination of the drug from the body. It is preferably consumed after a meal.
What Are the Side Effects of Tafenoquine?
Listed below are some of the common side effects encountered when consuming Tafenoquine.
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Nausea.
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Vomiting.
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Mood changes.
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Unusual dreams.
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Headache.
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Vision problems.
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Blurred vision.
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Sensitivity to light.
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Difficulty in falling asleep.
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Mental disturbances.
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Allergic reactions.
Some of the rare side effects can also be seen. In such cases, it is important to inform the healthcare professional immediately and get assistance.
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Hives.
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Breathing difficulty.
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Difficulty in swallowing.
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Hoarseness of voice.
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Throat tightness.
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Dark-colored urine.
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Confusion.
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Yellowing of skin and eyes.
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Hallucinations (visualizing non-existing things).
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Delusions.
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Lightheadedness.
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Swelling in the eyes, lips, and mouth.
Dietary Alterations:
Tafenoquine does not require any diet alterations unless specified by the doctor to improve overall health.
What Should Be Done When a Dose Is Missed?
It is always better to keep a reminder or set the alarm simultaneously every day to avoid missing a dose. In case of a missed dose, do not overdose on the drug. Always seek help from the health care professional before proceeding with the drug intake.
What Should Be Done to Treat Tafenoquine Overdose?
There is no specific antidote currently available for a drug overdose. However, gastric lavage is advised to wash the stomach and remove any drug remnants completely. It is extremely rare to overdose on this drug.
How to Store Tafenoquine?
The drug is stored at a temperature of 20 to 25 degrees Celsius. Store the drug in the original package to prevent moisture and cross-contamination. Keep the bottle tightly sealed, and do not remove the desiccant.
How to Handle Tafenoquine?
Tafenoquine should be handled cautiously. Avoid keeping in sunlight or extremely hot places. Tightly seal the container after usage. While dispensing the drug, use gloves or sterile instruments to avoid contamination.
How to Dispose of Tafenoquine?
The drug should be safely discarded after the completion of the treatment. Do not keep it accessible to children or pets to avoid unwanted consequences. It is important to call the biohazard waste management team and dispose of medical wastes. This prevents other people from consuming expired drugs without knowledge. Never flush the drug in the toilet, as it is not a safe disposal method. A thorough understanding of the Food and Drug Administration's safe disposal method can help properly manage medical and drug wastes.
Avoid Self-Medication:
It is quite common to take medication by self without consulting the doctors. However, self-medication can be harmful if not consumed in controlled doses. Hence it is always better and safer to consult a doctor and take the recommended dose. Also, it is important to complete the full course of the drug. Incomplete drug courses may increase the chances of drug intolerance.
For Doctors:
Indication:
The drug is specifically administered in patients with malaria. It has higher potency and better effects than other antimalarial drugs. It is also used in patients with a disease recurrence as a precaution. It can only be administered to individuals above 16.
Pharmacology:
Mechanism of Action:
The exact mechanism of action is still unknown. However, the active moiety of Tafenoquine is 5,6 ortho quinone which undergoes a redox reaction and is upregulated in gametocyte and liver stages. The oxidized form produces hydrogen peroxide and free hydroxyl radicals which is, in turn, responsible for the death of malarial parasites. In addition, the drug inhibits heme polymerase, which explains the drug's action during the blood stages of parasites.
Absorption:
The T-max of the drug is 13 hours, and prolonged absorption from the gut has been demonstrated with a slow clearance. The bioavailability of the drug increases in the presence of a high-fat meal. After absorption, the drug concentration there is a hike in the drug concentration in plasma, distributed to the liver.
Metabolism:
The drug is activated by the CYP2D6 enzyme, which the radicals reduce to ferredoxin - NADP reductase and flavin. However, in humans, the drug is metabolized in several pathways. The half-life of the drug is roughly 14 days.
Elimination:
After completely degrading the drug, it is excreted from the body via feces and urine. The renal elimination of the unchanged drug is usually low.
Toxicity:
The drug causes hemolysis in people with a medical condition called glucose-6-phosphate dehydrogenase deficiency. However, the drug is less carcinogenic in humans and lacks mutagenic potential.
Dosage and Administration of the Drug:
The drug is available in a 150-milligram capsule, which can be taken only through the oral route. The drug is preferred after food for its best effects. The doses can be altered depending on the height and weight of the patient. Also, the severity of the condition plays an important role in determining the frequency of drugs and dosage.
Considerations for Administration:
Special consideration is given to pregnant and breastfeeding mothers as it could cause defects in children. Also, elderly individuals and renal and hepatic impaired patients should be constantly monitored and advised of frequent follow-ups to avoid ill effects.
Contraindications:
The drug has to be avoided in the following cases as it causes serious side effects.
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Hypersensitivity reactions.
Drug Interactions:
There are no specific reports of drug interaction of Tafenoquine with other drugs. However, using Tafenoquine with other antimalarial drugs has better synergistic effects.
Other Specifications:
Tafenoquine in Pregnant Women:
The drug is unsafe for pregnant mothers, and some researchers have yet to conclude its safety. Hence it is better to avoid the drug during pregnancy. However, many alternative drugs can be used in such typical cases.
Tafenoquine in Lactating Women:
Lactating and breastfeeding mothers have higher chances of carrying the drug in their milk which can affect the children. Therefore, it is safer to avoid during feeding and prevent adverse effects.
Tafenoquine in Pediatric Patients:
The drug cannot be administered in pediatric patients. However, according to the FDA, an individual above 16 can use the drug under the doctor's prescription.
Tafenoquine in Geriatric Patients:
The drug can be used in elderly adults over 60 years of age. However, care should be taken to evaluate the individual's condition and pre-existing health issues properly. As most elders are immunologically compromised, the endurance of a small infection may cause severe discomfort.
Tafenoquine in Renal Impairment Patients:
The drug has to be given safely in adults with renal impairment as it is eliminated via the kidneys. However, poor kidney functions can result in drug accumulation in the body and may circulate in the bloodstream causing side effects. Therefore, a good history and additional blood tests must be performed before prescribing the drug so that there is proper elimination.
Tafenoquine in Hepatic Impairment Patients:
Like renal impairment, the drug has a mild effect on patients with hepatic impairment. Although there are fewer adverse effects, overlooking the condition can be unsafe. These adverse effects may vary with each individual and must be addressed well for the overall success of the treatment.
