SOPs in human trials: guidelines and best practices
Standard Operating Procedures are what turn a protocol from a plan into a repeatable, auditable reality. They ensure that tasks are carried out consistently regardless of who is doing them, and they are the first place an inspector looks when evaluating whether a study was conducted properly. A protocol describes what the study intends to do. An SOP describes how a specific task actually gets performed, by whom, and what happens when something goes slightly wrong along the way. Both matter, but only one of them is what a coordinator actually reaches for mid-visit.
Building good SOPs takes more effort upfront but saves a great deal of time (and risk) later. Here is a practical approach.
Start with the essential activities
Bring together a cross-section of the team and map out every critical process in the study. Take something like a site visit blood draw: what does it actually involve? Securing an appropriate room, meeting the participant, collecting the sample, processing and dispatching materials, cleaning up, and preparing for the next visit. Getting that level of detail down is the starting point.
Including people with different roles in this exercise matters. The PI sees the process differently to a research nurse, who sees it differently to admin staff. Each perspective surfaces things the others miss.
Draft roles and responsibilities
For each activity, work out who is responsible for what. This is not just a list of names: it should cover who acts, who oversees, who steps in when someone is absent, and what the handoff looks like.
Running this as an open forum (in person or virtual) helps surface gaps. Consider not just normal operations but edge cases: what happens if the internet goes down mid-visit? What if consumables have expired? What if the PI is unavailable?
Plan for failure modes
A SOP that only works when everything goes to plan is not a SOP: it is an optimistic assumption. Build in contingencies for the foreseeable failure modes. These scenarios often reveal where existing procedures are thin or where new SOPs are needed.
Walk through the process step by step
Map the sequence of steps and how they connect to related procedures. Then actually run through it with the team, ideally with role-play for the more complex interactions. Theoretical planning frequently misses things that become obvious the moment someone tries to follow the steps in sequence.
Test before you go live
Have staff implement the draft SOP before the study begins. Discover the gaps in a controlled environment rather than during participant visits. Pay attention to timing: steps that look quick on paper sometimes take longer in practice, and that can ripple through subsequent steps.
Keep SOPs current, and keep them from becoming pure box-ticking
ICH-GCP requires version control and regular review. A SOP that made sense at study setup may need revision as the study evolves, especially in longer-running trials. Review every six to twelve months as a minimum, and update whenever there is a protocol amendment or significant operational change.
It's worth being honest about a tension in the guidance itself here. A study surveying 327 GCP stakeholders across research spanning 124 countries found that while the guideline's global standardisation and clear investigator responsibilities were widely valued, its more prescriptive, checklist-style requirements were among the least helpful aspects reported: participants described them as discouraging and as creating excessive bureaucratic burden without a corresponding quality benefit. That's a useful check on SOP design specifically. An SOP written to satisfy an audit checklist, rather than to genuinely describe how the work gets done safely and consistently, tends to drift out of sync with real practice, which is exactly the gap an inspector is trained to spot.
What a well-maintained SOP set actually looks like
| Sign of health | Sign of drift |
|---|---|
| Staff can describe the SOP from memory in their own words | Staff read the SOP for the first time during an audit |
| Updated promptly after a protocol amendment | Still reflects an earlier version of the protocol |
| Reviewed on a set schedule (six to twelve months) | Only revisited after something has already gone wrong |
| Written from how the work is actually done | Written to satisfy a checklist, then never followed exactly |
A well-maintained set of SOPs does several things at once: it gives staff confidence, reduces expensive errors, improves audit readiness, and means the study can continue smoothly even when key personnel change. The time invested in getting them right, and in keeping them honestly aligned with how the work is actually carried out rather than how it looks on paper, is rarely wasted.