Provide the full names of patients who have been taking Penicillin V Potassium 250 MG since 1948.
full names = first, last; Penicillin V Potassium 250 MG refers to medications.DESCRIPTION = 'Penicillin V Potassium 250 MG'; since 1948 refers to substr(medications.START, 1, 4) > = '1948';
SELECT DISTINCT T1.first, T1.last FROM patients AS T1 INNER JOIN medications AS T2 ON T1.patient = T2.PATIENT WHERE T2.DESCRIPTION = 'Penicillin V Potassium 250 MG' AND strftime('%Y', T2.START) >= '1948'