A kitchen is a place where food is prepared and a sink is used to wash unused food remains from cutlery and other equipment. The drain and drain pipes are all part of the rubbish removal system.
So in the dream or vision, God showed you that the pill is in half because the other half of the pill (words) has no spiritual value or that it is bad and is only good to be washed down a drain. The eel symbolizes why it should not be eaten. The nature of an eel is to hide in holes and dark areas, waiting for its prey. When its unsuspecting prey comes too close, it suddenly strikes and kills it. This is what the pill does. The words that were prepared are bad and they will suddenly cause spiritual destruction in people’s lives.
So whatever the pill or the two halves represent (the words), it is not good for consumption. It should either be flushed down a drain or causes harm in people’s lives.
I do not know what triggered this dream but what I do know is that it represents specific prepared words (probably a teaching) that appear to be fine and good but in fact not good at all.