What is the alternative to suramin? Modern Replacements for Parasitic Infections

October 6, 2025 •

4 min read

First synthesized in 1916, suramin was a landmark antiparasitic drug, yet its use has significantly declined due to severe adverse effects, complex administration, and the development of more effective therapies. The question of what is the alternative to suramin is now answered by a range of modern medications tailored to specific diseases.

Quick Summary

Modern medicine offers several safer alternatives to suramin for parasitic infections, including ivermectin for river blindness and fexinidazole and NECT for African sleeping sickness, circumventing the older drug's toxicity and logistical challenges.

Key Points

Onchocerciasis Replacement: For river blindness, ivermectin has largely replaced suramin due to its much lower toxicity and simpler oral administration.
Oral HAT Treatment: The development of fexinidazole, an oral medication, has revolutionized the treatment of Human African Trypanosomiasis (HAT), as it is effective for both early and late stages and avoids invasive procedures.
NECT for Late-Stage HAT: Nifurtimox-Eflornithine Combination Therapy (NECT) is a key intravenous alternative for late-stage gambiense HAT, proving safer and more effective than eflornithine monotherapy.
Reduced Toxicity: Modern alternatives like ivermectin and fexinidazole have significantly better safety profiles than suramin, which causes severe side effects like nephrotoxicity and neurological issues.
Improved Accessibility: By replacing intravenous-only suramin, oral alternatives like ivermectin and fexinidazole make treatment more accessible in remote, low-resource settings where these parasitic infections are endemic.
Evolving Treatment Protocols: Due to the introduction of new drugs, older, highly toxic treatments such as suramin and melarsoprol are now reserved for specific, often more resistant, cases or where newer alternatives are not available.

Understanding the Need for Suramin Alternatives

Suramin is a venerable drug with a long history of use against parasitic diseases. However, its continued use has been eclipsed by its notable shortcomings. The drug is administered intravenously, which poses significant challenges in the remote, resource-limited areas where the diseases it treats, such as Human African Trypanosomiasis (HAT), are most prevalent. More importantly, suramin is known for its wide range of severe toxicities, including nephrotoxicity, peripheral neuropathy, and hypersensitivity reactions. The adverse effects are so pronounced that some patients must be hospitalized for monitoring during treatment, and a test dose is required to mitigate the risk of severe reactions. For these reasons, the development and adoption of safer, more effective alternatives have been a major focus of global health initiatives.

Modern Alternatives for Human African Trypanosomiasis (Sleeping Sickness)

Human African Trypanosomiasis (HAT), or sleeping sickness, is a parasitic disease caused by Trypanosoma brucei and transmitted by the tsetse fly. The appropriate suramin alternative depends on the infecting subspecies (gambiense or rhodesiense) and the stage of the disease (early vs. late, which affects the central nervous system). Suramin historically treated the early, hemolymphatic stage, as it does not cross the blood-brain barrier effectively.

Alternatives for Trypanosoma brucei gambiense (West and Central Africa)

Recent advancements have dramatically simplified the treatment for the more chronic T.b. gambiense form of HAT:

Fexinidazole: A major breakthrough, fexinidazole is an oral drug effective for both the first and second stages of T.b. gambiense HAT. This eliminates the need for a lumbar puncture to determine the disease stage in most cases, streamlining treatment dramatically. As a once-daily, 10-day oral regimen, it is far simpler to administer than older, more toxic therapies.
Nifurtimox-Eflornithine Combination Therapy (NECT): For second-stage HAT, NECT is a highly effective combination that is better tolerated and more effective than eflornithine monotherapy. It is administered via infusion over a 10-day period. While not oral, its improved safety and efficacy compared to older options make it a key treatment.
Pentamidine: An older alternative, pentamidine is used for the first-stage infection of T.b. gambiense. It is less toxic than suramin but also requires injection and is ineffective against second-stage disease.

Alternatives for Trypanosoma brucei rhodesiense (East and Southern Africa)

This form of HAT is more acute and aggressive. Newer guidelines reflect the availability of safer alternatives:

Fexinidazole: Similar to T.b. gambiense HAT, fexinidazole is the first-choice treatment for first and second stage rhodesiense cases in adults and children aged ≥ 6 years weighing ≥ 20 kg. Its oral administration marks a major improvement over historical treatments. Due to the high morbidity and mortality of rhodesiense HAT, relapse detection remains critical.
Melarsoprol: As a last-resort drug for second-stage rhodesiense HAT, the arsenical compound melarsoprol is used when no other option is available, such as in younger children. However, it is highly toxic, associated with a risk of fatal reactive encephalopathy, and its use is now largely restricted.

Replacing Suramin for Onchocerciasis (River Blindness)

Suramin was historically used to treat onchocerciasis, an infection caused by the filarial parasite Onchocerca volvulus, which is transmitted by the blackfly. However, it was replaced by a more effective and vastly safer oral alternative:

Ivermectin: This drug effectively kills the microfilariae (larval worms) that cause the symptoms of river blindness. Administered orally, it is much less toxic and easier to use than intravenous suramin. Unlike suramin, ivermectin does not kill the adult worms, requiring repeated treatments to manage the infection effectively.

Alternatives for Chagas Disease (American Trypanosomiasis)

While not a primary indication for suramin, the topic of antiparasitic alternatives often includes Chagas disease, caused by Trypanosoma cruzi. The treatments are different from those for HAT:

Benznidazole: This is a first-line medication for Chagas disease and is effective, especially when given early in the acute phase of infection.
Nifurtimox: This drug is also used to treat Chagas disease, often in conjunction with benznidazole.

Comparison of Suramin and Modern Alternatives


Feature	Suramin	Ivermectin	Fexinidazole	Nifurtimox-Eflornithine (NECT)
Route of Administration	Intravenous (IV)	Oral	Oral	Intravenous (IV)
Key Conditions Treated	Formerly HAT (early stage), Onchocerciasis	Onchocerciasis	HAT (gambiense and rhodesiense)	HAT (gambiense late stage)
Targeted Parasite	Trypanosoma brucei, Onchocerca volvulus (adult worms)	Onchocerca volvulus (microfilariae)	Trypanosoma brucei gambiense, T. b. rhodesiense	Trypanosoma brucei gambiense
Key Advantages of Alternative	N/A (older drug)	Oral, low toxicity, effective against microfilariae	Oral, effective against both early and late stages of HAT, circumvents lumbar puncture	Safer and more effective than eflornithine monotherapy, treats CNS stage
Major Disadvantages	High toxicity (nephrotoxicity, neuropathy), difficult IV administration	Requires repeated treatments as it doesn't kill adult worms	Side effects include gastrointestinal issues, potential QT prolongation	IV administration required, complex regimen

Conclusion

The move away from suramin represents a significant public health triumph, driven by the search for safer and more accessible treatments for neglected tropical diseases. For onchocerciasis, ivermectin provides a highly effective and well-tolerated oral alternative. For Human African Trypanosomiasis, the development of oral fexinidazole and the refinement of combination therapies like NECT have transformed patient care, offering better outcomes and dramatically reducing the risks associated with older drugs. While some highly toxic drugs like melarsoprol are still used in specific, limited circumstances, the overall trend in pharmacology is a clear shift toward modern medications that are not only more potent but also prioritize patient safety and ease of use in the field.

This article is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for specific medical concerns.

Frequently Asked Questions

Suramin was largely replaced due to its significant toxicity, including severe side effects like kidney damage and peripheral neuropathy, and its requirement for complicated intravenous administration.

Yes, for river blindness (onchocerciasis), ivermectin has almost completely replaced suramin. While suramin killed adult worms, ivermectin kills the microfilariae and is much safer and easier to administer orally.

The most significant modern alternative is fexinidazole. It is an oral drug that treats both the early and late stages of Human African Trypanosomiasis (HAT), offering a major advantage over older, more toxic, and injectable drugs.

Yes, the choice of alternative depends on the species of parasite (T.b. gambiense vs. T.b. rhodesiense) and the stage of the disease. For example, the Nifurtimox-Eflornithine Combination Therapy (NECT) is used for late-stage gambiense HAT.

In medicine, suramin's clinical use is extremely limited, primarily replaced by safer alternatives. However, it is being researched for other potential applications, including certain cancers and neurological disorders, though this is not a widespread or approved clinical practice.

While suramin wasn't a primary treatment, related antiparasitic drugs like benznidazole and nifurtimox are the standard therapies for Chagas disease, caused by Trypanosoma cruzi.

Generally, yes. Medications like ivermectin and fexinidazole have vastly better safety profiles than suramin, though they still have side effects. For example, fexinidazole can cause gastrointestinal issues and has a risk of QT prolongation.