Antimalarials: Nursing pharmacology

Antimalarials are a group of medications primarily used in the prevention and treatment of malaria, which is caused by Plasmodium spp, a protozoan parasite transmitted by certain Anopheles mosquitoes.

In addition, some antimalarials can also be used to treat amebiasis and some autoimmune disorders like systemic lupus erythematosus and rheumatoid arthritis.The oldest medication of this group is quinine, but its derivative chloroquine is most often used because it has fewer side effects.

Other antimalarials include hydroxychloroquine, mefloquine, primaquine, pyrimethamine, and a combination of atovaquone and proguanil.

If Plasmodium is resistant to antimalarial therapy, antibiotics like doxycycline, tetracycline, and clindamycin can be used.Antimalarials are administered orally.

Once administered, they work in various ways. Chloroquine, quinine, pyrimethamine, atovaquone, and proguanil all inhibit parasitic DNA synthesis; pyrimethamine, in particular, also inhibits protein synthesis.

Mefloquine and hydroxychloroquine affect the function of lysosomes in the parasitic cell. Finally, primaquine affects the mitochondria of the parasite.Antimalarials can cause a number of side effects, most commonly of the gastrointestinal tract such as nausea, vomiting, cramps, and anorexia.

In addition, clients can develop alopecia, a skin rash, photosensitivity, and hypersensitivity reactions like Stevens-Johnson syndrome and drug reaction with eosinophilia and systemic symptoms or DRESS for short.

Some clients taking antimalarials may also experience neurological side effects, such as headaches, nightmares, and even seizures; and mefloquine has a boxed warning for causing adverse neuropsychiatric reactions like anxiety, depression, hallucinations, and suicidal ideation.

Now, clients on antimalarials can often develop blurred vision and difficulty focusing due to damage to the cornea, while chloroquine and hydroxychloroquine can cause irreversible retinopathy.

Quinine, chloroquine, and hydroxychloroquine can cause vertigo, deafness, or tinnitus due to ototoxicity and damage to cranial nerve VIII.

High levels of quinine or primaquine can cause a condition known as cinchonism, which is characterized by nausea, vomiting, tinnitus, and vertigo.

On the other hand, pyrimethamine can cause megaloblastic anemia, thrombocytopenia, and leukopenia. Finally, some antimalarials like mefloquine may also cause cardiovascular side effects, including heart failure, sinus bradycardia, QT prolongation, first degree atrioventricular block, asystole, and torsade de pointes; and quinine can cause dangerous arrhythmias, as well as hemolytic anemia, renal insufficiency, and insulin release leading to hypoglycemia.When it comes to contraindications, primaquine should not be used in pregnancy and breastfeeding, while other antimalarials should be used with caution.

In addition, antimalarials should be used with caution in clients with hepatic or renal disease, as well as in those with myasthenia gravis, which might be exacerbated.

All these medications should also be used cautiously in children, as well as clients with hemolytic anemia, and glucose-6-phosphate dehydrogenase or G6PD deficiency.

Additional precautions should be taken with clients that have eye or skin disorders, as well as in those with neurologic, gastrointestinal, or cardiovascular disease.

Mefloquine should also be used with caution in clients with a history of depression. Regarding interactions, antimalarials should not be combined with any medication that is known to prolong the QT interval, as this can lead to arrhythmias.

Also, because pyrimethamine affects folate metabolism, it should not be used with antifolate medications like methotrexate or trimethoprim.All right, when caring for a client prescribed with the combination medication atovaquone and proguanil for malaria prophylaxis, first ask them about their travel plans, how long they will be in an area where malaria is endemic, and when they plan to return.

Then, perform a focused baseline assessment including vital signs, and review their most recent laboratory test results including CBC, renal, and hepatic function.

Next, explain to your client that atovaquone and proguanil can help prevent malaria by disrupting the parasite’s ability to make DNA, RNA, and proteins.

Then, instruct them to take one tablet daily at the same time each day, with food or milk. Let them know that if they vomit within one hour of taking their medication, that they should take another dose.

Advise them to start the medication one to two days before they enter the endemic area, and stress the importance of continuing the medication during their stay and for seven days after returning.

Lastly, ensure they understand the importance of adhering to their medication regimen, and to take other preventative measures to avoid mosquito bites, such as not being outdoors between dusk and dawn when mosquitoes are most actively feeding; using mosquito repellant and wearing clothing that reduces exposed skin; and sleeping under a bed net treated with the insecticide permethrin.

Now, be sure to remind your client about side effects they may experience, including headache, rash, and gastrointestinal disturbances like nausea and vomiting.

Lastly, emphasize the importance of seeking medical attention right away if they experience symptoms of malaria such as fever, chills, and muscle aches.

On the flip side, when your client has been diagnosed with malaria, they could be prescribed an antimalarial like chloroquine.

Before administration, complete a focused baseline assessment of your client’s malaria symptoms, and be sure to determine if your client has any current vision and hearing deficits.

Lastly, review your client’s most recent laboratory test results including CBC, renal and hepatic function; as well as diagnostic test results like Giemsa-stained blood smear examination.Next, explain to your client that chloroquine will treat their malaria infection by inhibiting the parasite's DNA replication.

Teach them that after they have taken their first dose of chloroquine, they should take their second dose six hours later; the third dose should be taken twenty-four hours after the initial dose; and then the fourth and final dose should be taken forty-eight hours after the initial dose.

Let them know that taking their medication with food can help prevent gastrointestinal upset. Lastly, stress the importance of adhering to their medication regimen and completing the entire course of treatment.

Then, let them know about some side effects they may experience. If abdominal discomfort or nausea occurs, explain that eating small, frequent meals throughout the day can help reduce these symptoms.

Teach them to immediately report symptoms of retinopathy like blurred vision, sensitivity to light, or difficulty focusing on objects; symptoms of ototoxicity like dizziness, decreased hearing, or ringing in their ears; as well as symptoms of hepatotoxicity like fatigue, nausea, anorexia, abdominal pain, dark urine, or yellowing of the skin or eyes.

Finally, be sure to monitor your client closely for side effects during treatment. Evaluate their adherence to the medication regimen and monitor for therapeutic effect of their medication.All right as a quick recap….

Antimalarials are a group of medications used in the prevention and treatment of malaria, caused by the Plasmodium spp, which is a protozoan parasite transmitted by certain Anopheles mosquitoes.

Antimalarials include quinine, chloroquine, hydroxychloroquine, mefloquine, primaquine, pyrimethamine, and the combination atovaquone and proguanil.

Antimalarials work in various ways to disrupt the life cycle of the parasite. Common side effects of antimalarials include gastrointestinal disturbances, alopecia, photosensitivity, skin rashes, and more severe side effects like Stevens-Johnson syndrome, DRESS, neuropsychiatric reactions, retinopathy, ototoxicity, and dysrhythmias.

Nursing considerations for clients prescribed antimalarials include assessing for effective prevention of malaria or therapeutic resolution of malaria symptoms while monitoring clients closely for side effects.

Client teaching is focused on safe self-administration, adherence to the treatment regimen, and recognition of serious side effects that need to be reported.