metronidazole – well known for causing nausea & vomiting plus tates nasty (& often causes metallic taste disturbance even when swallowed whole or given iv/rectally. Hence “after food” etc.
standard tabs are “only” film-coated which will allow rapid dispersal in the stomach anyway and there’s no sustained release product (breaking would have minor effect on absorption rates that’s clinically unimportant). Metronidazole is not especially iritant to your oesophagus.
However, product licenses state “swallow whole” and so that’s the advice imparted – you’ll be lucky to get anyone to divert from that formally, especially as there’s a liquid (still tastes orrible but taken on empty stomach), ‘shovers and also smaller (200mg) tabs.
(for the above reasons, and because I don’t know anything about you, the above are observations and not recommendations 😉 )