What is the role of doxycycline (antibiotic) in malaria (disease caused by Plasmodium spp.) prophylaxis?

From the Guidelines

Doxycycline is a recommended antimalarial medication for prophylaxis when traveling to regions with malaria risk, particularly in areas with mefloquine-resistant falciparum malaria. The recommended dosage is 100 mg once daily, starting 1-2 days before entering the malaria-endemic area, continuing throughout the stay, and for 4 weeks after leaving the area 1. This medication should be taken with food and plenty of water to reduce gastrointestinal side effects, and it's best taken at the same time each day to maintain consistent blood levels. Doxycycline works by inhibiting protein synthesis in the malaria parasite, preventing its reproduction. Important considerations include:

• Avoiding sun exposure due to increased photosensitivity risk
• Not taking with dairy products or antacids which can reduce absorption
• Being aware that it may reduce the effectiveness of oral contraceptives
• Contraindications in pregnant women, children under 8 years, and those with tetracycline allergies
• Common side effects include nausea, heartburn, and vaginal yeast infections While effective against most Plasmodium species, including chloroquine-resistant strains, it's essential to combine prophylaxis with mosquito bite prevention measures such as insect repellent, protective clothing, and bed nets for comprehensive protection 1.

From the FDA Drug Label

Doxycycline is indicated for the prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (<4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains Doxycycline offers substantial but not complete suppression of the asexual blood stages of Plasmodium strains. Patients taking doxycycline for malaria prophylaxis should be advised: that no present-day antimalarial agent, including doxycycline, guarantees protection against malaria. that doxycycline prophylaxis: should begin 1 to 2 days before travel to the malarious area, should be continued daily while in the malarious area and after leaving the malarious area, should be continued for 4 further weeks to avoid development of malaria after returning from an endemic area, should not exceed 4 months

Malaria Prophylaxis with Doxycycline:

• Doxycycline is indicated for the prophylaxis of malaria due to Plasmodium falciparum in short-term travelers to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains.
• The prophylaxis should begin 1 to 2 days before travel to the malarious area and continued daily while in the area and after leaving, for a total of 4 weeks after returning.
• It is essential to note that doxycycline does not guarantee protection against malaria and should be used in conjunction with other preventive measures, such as avoiding mosquito bites.
• The maximum duration of prophylaxis with doxycycline should not exceed 4 months 2 2.

From the Research

Malaria Prophylaxis with Doxycycline

• Doxycycline is a partially efficacious causal prophylactic agent against Plasmodium falciparum malaria, with a causal prophylactic efficacy rate of 67% 3.
• The drug is especially useful as a prophylaxis in areas with chloroquine and multidrug-resistant Plasmodium falciparum malaria 4.
• Doxycycline is not recommended for pregnant women and children < 8 years of age, but severe adverse events are rarely reported 4.
• A dosing regimen of doxycycline, 100 mg once daily, had an unacceptably high failure rate as a causal prophylactic agent against P. falciparum malaria in healthy, nonimmune volunteers 3.

Comparison with Other Antimalarial Agents

• Atovaquone-proguanil and doxycycline are the best tolerated regimens, while mefloquine is associated with adverse neuropsychiatric outcomes 5.
• Doxycycline users had fewer reported neuropsychiatric events than mefloquine users 5.
• Compared to chloroquine-proguanil, doxycycline had fewer reports of any adverse effect and gastrointestinal adverse effects 5.

Safety and Tolerability

• Doxycycline is generally well-tolerated, with few serious adverse events reported 4, 5.
• The most common adverse events associated with doxycycline are gastrointestinal symptoms, such as nausea and vomiting 5.
• Doxycycline is considered a safe option for malaria prophylaxis in non-pregnant adults and children over 8 years of age 4.