Benzodiazepines relative potency: which ranking is correct?

Benzodiazepines relative potency: which ranking is correct?

• A. Midazolam > Lorazepam > Diazepam
• B. Diazepam > Lorazepam > Midazolam
• C. Diazepam > Midazolam > Lorazepam
• D. Lorazepam > Midazolam > Diazepam

Answer: (D)

Potency means how much drug is needed to produce a given effect—the smaller the dose, the higher the potency. Lorazepam produces the desired sedative effect at a smaller dose compared with midazolam, and midazolam achieves a similar effect with less than diazepam. This reflects higher receptor affinity and efficacy for lorazepam, so a low dose can achieve hypnosis or strong sedation. Midazolam is very potent and fast-acting, but it still requires more milligrams than lorazepam to reach the same level of sedation. Diazepam, on the other hand, is less potent on a mg-for-mg basis and often needs larger doses to achieve comparable effect, partly because it has active metabolites that influence duration but not potency per se. Therefore, the ranking by potency is lorazepam greatest, then midazolam, then diazepam.

Potency means how much drug is needed to produce a given effect—the smaller the dose, the higher the potency. Lorazepam produces the desired sedative effect at a smaller dose compared with midazolam, and midazolam achieves a similar effect with less than diazepam. This reflects higher receptor affinity and efficacy for lorazepam, so a low dose can achieve hypnosis or strong sedation. Midazolam is very potent and fast-acting, but it still requires more milligrams than lorazepam to reach the same level of sedation. Diazepam, on the other hand, is less potent on a mg-for-mg basis and often needs larger doses to achieve comparable effect, partly because it has active metabolites that influence duration but not potency per se. Therefore, the ranking by potency is lorazepam greatest, then midazolam, then diazepam.