English to Spanish Medical Medical: Pharmaceuticals Study protocol

Buenas tardes:
Tengo dudas con el término "drop-in", no estoy segura de que en este contexto signifique "disminución". Alguna sugerencia?

See Section 21; patients who are tafamidis-naïve at baseline may opt to begin tafamidis treatment (ie, “tafamidis drop-in”) during the double-blind period.

Patients who are tafamidis naïve at baseline, but begin taking commercial tafamidis (ie, “tafamidis drop-in”), will remain in the study. Prior to commencing concomitant tafamidis, the investigator will perform assessments (including primary and select secondary efficacy assessments) at the Pre-tafamidis Drop-in Visit, as outlined in the Schedule of Assessments (Table 1). In all cases, the Pre tafamidis Drop-in Visit should occur prior to starting concomitant tafamidis;

Patients who are tafamidis-naïve at baseline may opt to begin tafamidis treatment (ie, “tafamidis drop-in”) during the double-blind period, which could result in a loss of power. An interim assessment may be performed to assess the impact of tafamidis drop-in on the power and the potential need to increase the sample size.

Desde ya muchas gracias!