There are these:
PD3 The magnitude of pleasure reaches its limit in the removal of all pain. When pleasure is present, so long as it is uninterrupted, there is no pain either of body or of mind or of both together.
PD4 Continuous pain does not last long in the flesh; on the contrary, pain, if extreme, is present a very short time, and even that degree of pain which barely outweighs pleasure in the flesh does not last for many days together. Illnesses of long duration even permit of an excess of pleasure over pain in the flesh. (well it's not pleasure but it's continuous, fwiw)
Usener 116 from Cassius , Usener 146 from Charles , and PD 4 both use the word συνεχώς or a variation. The problem is it has a wide range of meanings! Continuous, continually, without interruption, at frequent intervals, etc.
PD3 doesn't actually have a word meaning continuous! Here's my clunky literal transition of PD3:
"The limit of the degree of pleasure (is) the whole of the removal of that which causes pain. Where that which gives pleasure exists, during the time it is present, there is not bodily pain nor that which disturbs the mind nor either of these together."