Después de regulaciones (not many hits but fits the context)
Long shot but after researching, I see it to mean patient has been taking 20 mg of memantine since June 2021, and it is a medication that is increased to that amount.

How and when to take memantine
NHS
https://www.nhs.uk › Medicines A to Z › Memantine
13
Dosage and strength · one 5mg tablet, once a day. This is usually increased by 5mg every week until your dose is 20mg. ·

For treatment of Alzheimer's disease:
For oral dosage form (extended-release capsules):
Adults—At first, 7 milligrams (mg) once a day. Your doctor may gradually increase your dose as needed. However, the dose is usually not more than 28 mg per day.
https://www.mayoclinic.org/drugs-supplements/memantine-oral-...

Alzheimer-Type Dementia
Treatment of moderate-to-severe dementia

Tablet: 5 mg PO once daily initially; increased by increments of 5 mg/day each week; maintenance target dosage (>5 weeks): 20 mg/day PO divided q12hr

Extended-release capsule: 7 mg PO qDay initially; may be increased by increments of 7 mg/day each week; maintenance target dose is 28 mg PO qDay

Dosage Modifications
Renal impairment
Mild or moderate: No dosage adjustment required
Severe: (CrCl 5-29 mL/min): Not to exceed 14 mg/day (extended-release) or 5 mg BID (prompt-release)

Agree that dsps is most likely después, so closest to fit regs is regulaciones, here used in similar context:

La regulación de la dosis se debe hacer
con cautela y la dosis se debe aumentar gradualmente con una vigilancia cuidadosa
https://cima.aemps.es/cima/pdfs/es/ft/17128/FT_17128.html.pd...