From the FDA Drug Label
After oral administration >90% of diazepam is absorbed and the average time to achieve peak plasma concentrations is 1 – 1.5 hours with a range of 0.25 to 2. 5 hours.
The time to take diazepam (Valium) prior to an MRI for anxiety is not explicitly stated in the drug label. However, based on the pharmacokinetics of diazepam, it can be inferred that:
- The average time to achieve peak plasma concentrations is 1-1.5 hours.
- The range of time to achieve peak plasma concentrations is 0.25 to 2.5 hours. Considering this information, it is recommended to take diazepam at least 1-2 hours before the MRI to allow for peak plasma concentrations to be reached, but this is not a direct answer from the label. 1
From the Research
Valium (diazepam) should typically be taken 30-60 minutes before an MRI procedure to manage anxiety, as this allows for peak effectiveness during the scan, according to the most recent and highest quality study available 2. The medication usually begins working within 15-30 minutes, but allowing up to an hour ensures optimal anxiolytic effects.
- The standard dose for MRI-related anxiety is usually 2-10 mg, though this should be determined by your healthcare provider based on your medical history, body weight, and anxiety severity.
- Always follow your doctor's specific instructions regarding timing and dosage.
- Valium works by enhancing the effects of GABA, a neurotransmitter that inhibits brain activity, helping to reduce anxiety and promote relaxation during the confined and noisy MRI experience.
- Be aware that you'll need someone to drive you home after the procedure, as Valium causes drowsiness and impairs your ability to drive safely.
- Also, inform your doctor about any other medications you're taking to avoid potential interactions. It's worth noting that the use of a wide-bore magnet can also increase the odds of successfully completing the MRI Brain examination in mild, moderately, and severely claustrophobic patients, as shown in a recent study 2. However, the efficacy of low-dose oral benzodiazepine is limited to severely claustrophobic patients, highlighting the importance of individualized treatment plans.