Medicines in Clinical Practice
Controlled drugs, dependence, misuse and additional safeguards
Applied learning on controlled drugs, dependence, misuse and additional safeguards.
Learning objectives
• Explain why controlled medicines require additional clinical and governance safeguards. • Assess benefit, harm, dependence, diversion and overdose risk without stigmatising the patient. • Prescribe and review controlled medicines with clear indication, documentation and follow-up. • Distinguish physical dependence, tolerance, substance-use disorder and diversion. • Respond proportionately to lost medicines, early requests, unsafe combinations and suspected misuse.
Overview
Learning objectives
- Explain why controlled medicines require additional clinical and governance safeguards.
- Assess benefit, harm, dependence, diversion and overdose risk without stigmatising the patient.
- Prescribe and review controlled medicines with clear indication, documentation and follow-up.
- Distinguish physical dependence, tolerance, substance-use disorder and diversion.
- Respond proportionately to lost medicines, early requests, unsafe combinations and suspected misuse.
Why controlled medicines need extra care
Controlled medicines can be essential and highly effective, but some carry increased risks of dependence, overdose, diversion, misuse and harm if storage or supply is poorly managed. Legal controls add safeguards around prescribing, supply, storage and record keeping. The clinical goal is not to make access unnecessarily difficult; it is to ensure that treatment remains justified, safe and accountable.
Start with a clear indication and treatment goal
Before initiating or continuing a controlled medicine, establish the current indication, expected benefit, alternative options, relevant comorbidities, concurrent medicines and the patient’s understanding. Document the regimen and the plan for review. NICE guidance emphasises assessing benefits and risks, including dependence, overdose and diversion, and considering other prescribed and non-prescribed centrally acting medicines.
Dependence is not the same as addiction
Physical dependence can develop with several medicine classes and may produce withdrawal if treatment is stopped abruptly. Tolerance may lead to reduced effect at the same dose. Substance-use disorder involves a broader pattern of impaired control and harmful use. These concepts should not be collapsed into one label. Stigmatising language can damage trust and may itself make safe care harder.
Review should test continuing value
Repeat prescribing should not become automatic. Review whether the medicine is still achieving its intended benefit, whether function or symptoms have improved, whether harms are emerging, whether the dose has escalated, whether monitoring is complete and whether the person is using other sedating or interacting substances. A medicine can remain clinically appropriate despite long-term use, but the justification should be explicit rather than assumed.
Early requests, lost medicines and inconsistent histories
An early request or report of lost medication is a safety signal, not proof of misuse. Check dispensing history where available, clarify what happened, assess withdrawal and clinical risk, consider safeguarding or diversion concerns, and follow local controlled-drug policy. Repeated patterns may require a more structured prescribing arrangement, smaller quantities, single prescriber/pharmacy arrangements or specialist input. Avoid punitive abrupt cessation when this would create foreseeable harm.
High-risk combinations and respiratory depression
Risk can rise substantially when opioids, benzodiazepines, Z-drugs, gabapentinoids, alcohol or other CNS depressants are combined, particularly in frailty, respiratory disease, sleep-disordered breathing or renal impairment. Wales prescribing indicators and 2026 gabapentinoid resources explicitly highlight these risks. The response should be individualised: reassess indication, cumulative sedation, dose, renal function, monitoring and deprescribing opportunities.
Sources for this module
Legal and organisational safeguards
Controlled-drug rules vary by schedule, setting and activity, and legislation changes. Clinicians should use current BNF, legislation, organisational policy and pharmacy advice rather than relying on remembered technical rules. Prescriptions, when-required directions, storage, disposal and incident reporting may have additional requirements. If unsure, seek advice before creating an unsafe workaround.
Practical reasoning framework
Ask: Why is this controlled medicine needed now? What benefit is being demonstrated? What harms or dependency risks are present? Are there interacting sedatives or substances? Is the supply pattern consistent with the agreed plan? What monitoring and review are needed? Is there any safeguarding or diversion concern? What would happen if treatment were suddenly interrupted?
Sources for this module
- NICE NG46 - Controlled drugs: safe use and management.
- GMC - Good practice in proposing, prescribing, providing and managing medicines and devices.
- AWTTC - National Prescribing Indicators 2025-2028.
- AWTTC - All Wales gabapentinoid resources for chronic pain (May 2026).
- Current UK controlled-drug legislation, BNF and local controlled-drug policies.
Educational note: medicine-specific doses, thresholds, contraindications and rapidly changing regulatory requirements must be checked against current authoritative guidance and local policy at the point of care.
