IRT, IWRS, IVRS and RTSM are used loosely and often interchangeably. Underneath are two jobs: assigning participants to a treatment, and managing the supply of the product they receive. Knowing which job you need decides whether your EDC is enough.
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Participant eligible
Consent and screening complete
Randomization
Arm assigned by algorithm, strata applied, blinded
Product assignment
Which pack or kit, when it expires
Supply management
Depot stock, resupply, expiry, returns
Reconciliation
Accountability against randomization record
The short answer
The vocabulary
The terms evolved with the technology. In the 1990s, sites called an automated phone line to randomize a participant: IVRS, interactive voice response system. When the web took over, IWRS (interactive web response system) appeared. IRT combined both under one name. RTSM emerged later, often used by vendors and sponsors who wanted to say plainly that the system does randomization and supply management, not just a randomization call. The glossary entry for IRT and IWRS gives the short definition.
There is no regulatory distinction between the names. When a protocol says IRT, check the specification, because the real question is which functions are expected. When a vendor says RTSM, ask whether supply management is part of the quote.
Quick reference
| Term | Stands for | What it usually means |
|---|---|---|
| IVRS | Interactive voice response system | Phone-based randomization or dispensing. Rare now as a standalone interface. |
| IWRS | Interactive web response system | Web-based randomization and, often, drug assignment. |
| IRT | Interactive response technology | The umbrella term for IVRS, IWRS and combined systems. |
| RTSM | Randomization and trial supply management | Randomization plus product supply: stock, depots, resupply, expiry, returns. |
| Randomization module | A function inside an EDC or other platform | Assigns arms from a list or algorithm and records the allocation. |
Usage varies by sponsor and vendor. Always rely on the written functional specification.
Scope
Randomization assigns each participant to an arm using the method in the protocol: simple, blocked, stratified, minimisation or others. It must be unpredictable to sites, auditable and, in blinded trials, must keep the allocation hidden from those who should not see it. See clinical trial randomization software and block randomization software.
Supply management is logistics under regulation. It covers forecasting need, shipping to depots and sites, tracking batch and expiry, assigning specific units to participants, handling temperature excursions and returns, and reconciling what was dispensed. The complexity grows with the number of sites, countries, products and dosing changes. For accountability records on the site side see IMP inventory and drug accountability software.
Because the jobs are separable, a good question for any vendor or protocol is which of these two it covers. A specification that says IRT but describes only randomization needs different software from one that includes resupply algorithms.
| Single-site pilot | Multi-site, one product | Multi-country, blinded, titration | |
|---|---|---|---|
| Randomization with strata | |||
| Blinded allocation concealment | |||
| Depot-to-site shipment tracking | |||
| Automated resupply triggers | |||
| Dose-level titration logic | |||
| Expiry and batch-level assignment |
Decision rule
Work down the rows. The first row you cannot answer yes to is the point where a dedicated RTSM starts to earn its cost.
| Question | If yes | If no |
|---|---|---|
| Is randomization the only automated function the protocol needs? | EDC randomization can cover it. | Look at RTSM features below. |
| Can the pharmacy hold and label product centrally, or is it simple site stock? | Site-level accountability on paper or in the EDC may be enough. | You need depot and site tracking. |
| Is the product the same for every participant, or are packs interchangeable? | No unit-level assignment needed. | You need kit or pack assignment. |
| Are there few sites and one country? | Manual resupply is manageable. | Automated forecasting and resupply help. |
| Is the study open-label or does a pharmacist handle blinding? | Blinding managed outside the system is feasible. | System-enforced allocation concealment is worth paying for. |
| Are dose changes or titration steps assigned by the system? | No. | Dedicated RTSM or custom build. |
A hybrid is common: EDC randomization plus a separate supply log or a vendor system used only for shipping.
Set up arms, strata and allocation in the free Capture sandbox and test the flow from consent to randomization with demo participants. Free, every feature, no credit card.
Where Capture fits
Capture is a self-serve EDC, eCRF, ePRO, eConsent and randomization platform with one audit trail. Randomization sits beside the eCRFs, so eligibility, consent and allocation are in one record. Blinded roles never receive treatment-arm values; this is enforced by masked database views and row-level security, not just by hiding a column in the interface.
Study status Live
Site activated Yes
Randomization list 42 allocations left
Has the subject signed the current informed consent?
Go deeper
A short definition of the terms.
Read more DefinitionWhat randomization is and why it exists.
Read more GuidePractical options when you have few sites.
Read more CompareA named IRT vendor comparison.
Read more CompareA named supply and IRT provider comparison.
Read more GuideRunning allocation yourself, safely.
Read moreProcurement
Write the functional scope before you contact vendors. List the randomization method, strata, blinding model, product types, number of depots and sites, resupply rules and reports needed. Ask each vendor to price randomization and supply separately, and ask what happens at amendments, because changes to arms or strata mid-study are where costs appear.
Ask also about integration with the EDC: how eligibility reaches the randomization system, how the allocation returns to the casebook and who reconciles differences. A platform where randomization is native avoids that integration. See EDC with randomization and the randomization list generator for hands-on options.
IRT is the umbrella term for interactive systems used to randomize and assign product. RTSM spells out the scope: randomization and trial supply management. In practice vendors use them for the same category, so check the functional specification.
IWRS is an interactive web response system, the web version of the older phone-based IVRS. It lets site staff randomize participants and, in many setups, assign product through a web interface.
If your protocol needs only randomization, an EDC with built-in randomization may be enough. If you need blinded product assignment, depot management, resupply or titration logic across many sites, you probably need a dedicated RTSM.
For randomization, often yes. For complex supply management, usually not. Decide by listing which functions your protocol and pharmacy manual require.
This page makes no supply management claim for Capture. Capture includes randomization with blinding enforced at the data layer. Discuss supply needs in a demo and see the RTSM page for details.
In well-designed systems the allocation is concealed from roles that should not see it, and enforced by access rules rather than interface layout. In Capture, blinded roles never receive treatment-arm values, enforced by masked database views and row-level security.
In everyday use yes. Randomization is the process of assigning an arm; product assignment links that arm to a specific pack or kit, which is a supply function.
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