Table 2.

Summary of two potential antiviral drugs for monkeypox.

Name	Tecovirimat	Brincidofovir, BCV
Synonym	Tpoxx®, ST-246	Tembexa®; Hexadecyloxypropyl-cidofovir (HDP-CDV), CMX001
US FDA approval	July 2018 for human smallpox	June 2021 for human smallpox
Pharmacological preparation	Capsule: 200 mg Injection: lyophilized powder for reconstitution, 200mg/20 mL	Tablet: 100 mg Oral suspension: 10 mg/mL
Mechanism	Inhibit extracellular virus formation and prevent cell–cell and long-distance spread	A pro-drug of cidofovir conjugated with a lipid molecule; in infected cells, transformed into cidofovir diphosphate to inhibit DNA polymerase-mediated DNA synthesis and incorporate into the growing viral DNA chain, slow viral DNA synthesis rate
Treatment dose and duration	Oral - take within 30 min after eating full meal ●40 kg to <120 kg: 600 mg BID for 14 days ●≥120 kg: 600 mg TID for 14 days Intravenous dosing - ●35 kg to <120 kg: 200 mg over 6 h q12 h for 14 days ●≥120 kg: 300 mg over 6 h q12 h for 14 days	●≥48 kg (tablet or oral suspension): 200 mg PO x 2 doses (on Day 1 and 8) ●<48 kg (oral suspension): 4 mg/kg PO x 2 doses (on Day 1 and 8)
Renal or hepatic adjustment	Renal impairment ●Oral: mild, moderate, severe, or patients requiring hemodialysis: no dosage adjustment required ●Intravenous: mild-to-moderate (CrCl 30–89 mL/min), no dosage adjustment necessary; severe (CrCl <30 mL/min), contraindicated Hepatic impairment ●Mild, moderate, or severe (Child-Pugh class A, B, or C): no dosage adjustment required	Renal or hepatic impairment: no dosage adjustment required with any degree of impairment
Pharmacokinetics	●Plasma protein binding: 77.3%–96.3% ●Route of elimination: feces (71–75%) and urine (18–24%) at 96 h post dose	Oral 100 mg tablet: Cmax, 251 ng/mL; area under curve, 1394 ng h/mL; oral bioavailability: 13.4% in tablet and 16.8% in suspension
Drug–drug interaction	●May induce certain CYP enzymes, including CYP3A4, and its metabolites (M4 and M5) have the potential to produce drug–drug interactions by the induction of CYP2B6 ●Increased effect of repaglinide; decrease effectiveness of midazolam	Concomitant use with OATP1B1 and 1B3 inhibitors increase BCV-associated adverse reactions
Efficacy in animal study	Survival rate of cynomolgus macaques with tecovirimat treatment at 5, 6, 7, or 8 days following monkeypox virus challenge: 100%, 67%, 100%, and 50%	Survival rate of prairie dogs intranasally challenged by monkeypox virus on the day of BCV therapy relative to inoculation day: 57% on ID-1, 43% on ID0, and 29% on ID1
Adverse drug reactions	●Oral: headache, osteoarthritis, and hidradenitis ●Intravenous: infusion site pain, swelling, erythema, extravasation; headache	Mild gastrointestinal events, such as diarrhea, nausea, vomiting, abdominal pain

CrCl: creatinine clearance; CYP: cytochrome; ID-1: 1 day prior to viral challenge; ID0: the day of challenge; ID1: one day after viral challenge.

US FDA: Food and Drug Administration, United States.