In conscious sedation (CS) procedures, the patient is sedated but retains the ability to breathe spontaneously. Drug-induced ventilatory depression represents a dangerous side effect of CS, possibly leading to hypoventilation and subsequent hypoxia. In this work, we propose a new pharmacodynamic model for drug-induced ventilatory depression. The model presents a parsimonious structure and shows good agreement with experimental data for different drugs. In addition, we explore the innovative idea of regulating drug infusion during CS by means of a feedback control system based on measurements of transcutaneous partial pressure of CO(2). In simulations, the controller proves able to maintain a predefined target of CO(2) despite pain, external disturbances and inter-patient variability in the sensibility to the drug. The implementation of the controller during CS procedures would improve clinical practice minimizing the occurrence of drug-induced ventilatory depression by tailoring drug infusion to patient's needs.