15.— Nothing in this Part shall be construed to affect a pharmacist’s discretion, when presented with a prescription, to not dispense, whether temporarily or permanently, a medicinal product in accordance with the prescription (including any substitute medicinal product) if, in his or her professional opinion as a pharmacist, the prescription ought not to be dispensed because to do so may be prejudicial to—

(a) the health of the patient for whom the prescription was written, or

(b) the health or safety of members of the public.