Historically, the fundamental role of pharmacists as a healthcare practitioner was to check and distribute drugs to doctors for medication that had been prescribed to patients. In more modern times, pharmacists advise patients and health care providers on the selection, dosages, interactions, and side effects of medications, and act as a learned intermediary between a prescriber and a patient. Pharmacists monitor the health and progress of patients to ensure the safe and effective use of medication. Pharmacists may practice compounding; however, many medicines are now produced by pharmaceutical companies in a standard dosage and drug delivery form. In some jurisdictions, pharmacists have prescriptive authority to either independently prescribe under their own authority or in collaboration with a primary care physician through an agreed upon protocol.