Artesunate is a prodrug that is rapidly converted to its active form dihydroartemisinin (DHA). This process involves hydrolysis of the 4-carbon ester group via plasma esterase enzyme. It is hypothesized that the cleavage of endoperoxide bridge in the pharmacophore of DHA generates reactive oxygen species (ROS), which increases oxidative stress and causes malarial protein damage via alkylation. In addition, Artesunate potently inhibits the essential Plasmodium falciparum exported protein 1 (EXP1), a membrane glutathione S-transferase. As a result, the amount of glutathione in the parasite is reduced.In 2016, artemisinin has been shown to bind to a large number targets, suggesting that it acts in a promiscuous manner. There is evidence suggesting DHA inhibition of calcium-dependent ATPase on endoplasmic membrane, which disrupts protein folding of parasites. Pharmacokinetics
In infected individuals, the elimination half-life of artesunate is about 0.22 hours. Its active metabolite, DHA, has a slightly longer half-life of 0.34 hours. Overall, the average half-life ranges from 0.5 to 1.5 hours. Because of its short half-life, its use in malaria prevention is limited.DHA is metabolized to an inactive metabolite by the liver enzymes CYP2B6, CYP2C19, and CYP3A4. Chemical synthesis
Artesunate is made from dihydroartemisinin (DHA) by reacting it with succinic acid anhydride in a basic medium. It is one of few semi-synthetic derivatives from artemisinin that is water-soluble. Research
In 2007, the FDA approved an Investigational New Drug (IND) protocol for intravenous artesunate.Artesunate is under study for the treatment of cancer and COVID-19. History
In May 2020, artesunate was approved for medical use in United States.
The narrowing of the passageway may cause constipation, straining, and thin stools.Herpes Simplex Virus 1 and 2 (herpes proctitis)

Symptoms may include multiple vesicles that rupture to form ulcers, tenesmus, rectal pain, discharge, hematochezia. The disease may run its natural course of exacerbations and remissions but is usually more prolonged and severe in patients with immunodeficiency disorders. Presentations may resemble dermatitis or decubitus ulcers in debilitated, bedridden patients. A secondary bacterial infection may be present.Syphilis (syphilitic proctitis)

The symptoms are similar to other causes of infectious proctitis; rectal pain, discharge, and spasms during bowel movements, but some people may have no symptoms. Syphilis occurs in three stages. The primary stage: One painless sore, less than an inch across, with raised borders found at the site of sexual contact, and during acute stages of infection, the lymph nodes in the groin become diseased, firm, and rubbery. The secondary stage: A contagious diffuse rash that may appear over the entire body, particularly on the hands and feet. The third stage: Occurs late in the course of syphilis and affects mostly the heart and nervous system. Causes
Proctitis has many possible causes. It may occur idiopathically (idiopathic proctitis, that is, arising spontaneously or from an unknown cause). Other causes include damage by irradiation (for example in radiation therapy for cervical cancer and prostate cancer) or as a sexually transmitted infection, as in lymphogranuloma venereum and herpes proctitis. Studies suggest a celiac disease-associated "proctitis" can result from an intolerance to gluten.