This code system http://hl7.org/fhir/medication-request-status defines the following codes:

CodeDisplayDefinition
activeActiveThe prescription is 'actionable', but not all actions that are implied by it have occurred yet.
on-holdOn HoldActions implied by the prescription are to be temporarily halted, but are expected to continue later. May also be called "suspended".
cancelledCancelledThe prescription has been withdrawn.
completedCompletedAll actions that are implied by the prescription have occurred.
entered-in-errorEntered In ErrorThe prescription was entered in error.
stoppedStoppedActions implied by the prescription are to be permanently halted, before all of them occurred.
draftDraftThe prescription is not yet 'actionable', i.e. it is a work in progress, requires sign-off or verification, and needs to be run through decision support process.
unknownUnknownThe authoring system does not know which of the status values currently applies for this request