Are there any prescription drugs that can be used for bedwetting in a young child (8yo)?

Yes: A child at least 7yr old, with primary enuresis (meaning he's always been a bed-wetter), can do a trial of DDAVP (desmopressin) tablets, after being seen by a pediatrician to make sure there isn't another medical cause for bed-wetting. Bed-wetting runs in some families, and is a developmental problem that children will outgrow. Ddavp (desmopressin) can reduce or prevent enuresis while parents wait for the child to mature more.

Yes-try retrain 1st: Your child is old enough for medication, but best try other methods first like restricting fluids after supper and taking to toilet after couple of hrs. Best proven cure is bedwetting alarm. This attaches to underpants and buzzes +/or vibrates to wake child. In time child "hears" alarm before it goes off and they either wake or hold it in. Meds are; demopressin(ddavp), Imipramine or oxybutininer.