Electronic Prescribing (eRx) Fundamentals
A prescription is the first data exchange in a patient's medication journey. This is a plain-language explainer of the standard that carries it — NCPDP SCRIPT — the e-prescribing workflow, the added safeguards for controlled substances under EPCS, and why medication history is one of the quiet workhorses of patient safety.
What electronic prescribing actually is
From the clinician's screen to the pharmacy queue
Electronic prescribing (eRx) is the secure, structured transmission of a prescription directly from a prescriber's system to a pharmacy — replacing paper, faxes and phoned-in orders. The transactions are defined by the NCPDP SCRIPT standard, maintained by the National Council for Prescription Drug Programs. SCRIPT specifies the message format for a new prescription, a refill request and response, a change request, a cancellation, and more — so a prescriber's software and a pharmacy's software can exchange a prescription unambiguously, even when they come from different vendors.
For the Medicare Part D program, CMS adopted NCPDP SCRIPT version 2017071 effective January 1, 2020, retiring the older version 10.6. A newer version, 2023011, has been named for the next transition, extending support for transactions such as electronic prior authorization. AzHeC tracks these versions but does not favor any one prescribing system — the value is in the shared standard, not the brand on the screen.
The e-prescribing workflow, step by step
A routine new prescription moves through a predictable set of SCRIPT transactions.
1 · Prescriber composes the order
The clinician selects the medication, dose, quantity and instructions in the EHR or prescribing system, with drug-interaction and allergy checks running in the background.
2 · NewRx is transmitted
The order is encoded as an NCPDP SCRIPT NewRx message and routed — typically through an e-prescribing network — to the patient's chosen pharmacy.
3 · Pharmacy receives and verifies
The pharmacy system ingests the structured message, the pharmacist verifies it, and the medication is prepared. No re-keying of a faxed or handwritten order is required.
4 · Status and changes flow back
SCRIPT supports a fill-status notification (RxFill), a change request (RxChange) when a substitution or clarification is needed, and a cancel transaction — so both sides stay synchronized.
5 · Refills are handled in-band
When a refill is due, the pharmacy sends a refill request and the prescriber responds electronically, closing the loop without a phone call.
EPCS adds DEA-grade safeguards
Electronic prescribing of controlled substances (EPCS) uses the same NCPDP SCRIPT transport but layers on security required by the U.S. Drug Enforcement Administration: two-factor authentication of the prescriber, a digital signature on the prescription, and identity-proofing of the individual signing it. Software used for EPCS must be audited or certified against the DEA's requirements before it can transmit controlled-substance prescriptions.
EPCS is now central to fighting prescription fraud and supporting safer opioid prescribing. CMS has set program thresholds requiring most Part D controlled-substance prescriptions to be transmitted electronically. AzHeC explains these requirements neutrally so Arizona stakeholders understand the obligation, not to sell a path to it.
Medication history: the safety dividend
Knowing what a patient is already taking
NCPDP SCRIPT also carries a medication history transaction, letting a prescriber or pharmacy pull a patient's recently dispensed medications from across the network. At the point of care this is one of the highest-value pieces of interoperable data: it surfaces drug-drug interactions, duplicate therapies and adherence gaps that a single-system view would miss. Combined with the longitudinal record available through a statewide health information exchange, medication history helps reconcile what a patient is actually taking — a recurring source of preventable harm during transitions of care.
Frequently asked questions
01What is NCPDP SCRIPT?
It is the national standard, maintained by the National Council for Prescription Drug Programs, that defines the format of e-prescribing messages — new prescriptions, refills, changes, cancellations, fill notifications and medication history — so prescriber and pharmacy systems can exchange them reliably.
02How is EPCS different from regular e-prescribing?
EPCS handles controlled substances and adds DEA-mandated safeguards: two-factor authentication, a digital signature on the prescription, identity proofing of the prescriber, and audit or certification of the software used.
03Does e-prescribing replace the pharmacist's judgment?
No. eRx improves the accuracy and traceability of the transmission and the data available, but verification, clinical review and dispensing remain the pharmacist's responsibility.
Continue through the medication loop
A prescription draws down physical stock and triggers replenishment. Next, see how the drugs behind it move through a serialized, traceable supply chain.