Sentry Capguard (nitenpyram) Oral Flea Control Medication Treat Flea Infestations With One Easy Tablet. Fast acting, starts working in 30 minutes Contains Nitenpyram, Veterinarian Recommended. Kills Adult Fleas On Your Pet Easy-To-Dose Tablet Format, No Mess, Can't Rub Or Wash Off NADA 141-175 - Approved by FDA.