As a fifth level spell, it's definitely overpowered. Compare with Power Word Stun, a 7th level spell that can stun for longer durations (depending on HP), but doesn't do damage and most importantly doesn't affect creatures that have more than a certain number of HP.
Effects that prevent a target from acting without allowing a save should be high level and/or be very limited in what they can affect. This spell is neither.
Effects that prevent a target from acting without allowing a save should be high level and/or be very limited in what they can affect. This spell is neither.