Medication products in Patients - Medical Records - Summary can be edited.
This should be prevented, if the product is linked to an invoice item, as it causes reconciliation issues:
the invoice item product and medication product are different
the Patient Medical Records - Summary price displayed doesn't correspond to the product
This behaviour exists for historical reasons; it provided a way to amend incorrectly dispensed products post invoice finalisation. In 1.9 however, a more appropriate technique to use would be an Addendum record to annotate the incorrect product