There's no requirement in ICD-10 to sequence diagnosis codes in any particular order. The only requirements are that you select the principle or first-listed code which represents the main reason for the service or encounter, and that you following any specific 'code first' instructions within ICD-10 when a particular code requires another code to be listed first. In addition, there are some codes that can only be used in the first position, but beyond that, the sequencing of additional codes does not affect reporting or payment and is arbitrary.
Per the ICD-10 guidelines, the long term use of a medication should be coded when it is documented that the use of that medication affected treatment or required care at the particular encounter you are coding. Many coders will sequence the 'Z' codes last since those represent a status rather than a diagnosis or condition, but that's not a specific requirement and it shouldn't be considered an error if they are not in a particular order.