Temazepam Capsule Formulation
Temazepam capsules contain the active drug mixed with inactive powder excipients (corn starch, lactose, magnesium stearate, sodium lauryl sulfate), not multiple-sized beads. 1
Capsule Contents and Manufacturing
The FDA-approved temazepam formulation uses a powder blend system rather than a bead-based delivery mechanism 1. The capsule contains:
- Active ingredient: Temazepam USP (7.5 mg, 15 mg, 22.5 mg, or 30 mg)
- Inactive ingredients: Corn starch, lactose anhydrous, magnesium stearate, and sodium lauryl sulfate 1
- Capsule shell: Gelatin with various colorants depending on strength (FD&C dyes, titanium dioxide) 1
This differs fundamentally from controlled-release formulations that use bead technology. For example, some ADHD medications employ "a combination of immediate-release and delayed-release beads" to achieve extended duration 2, but temazepam does not use this approach.
Formulation Variations
Soft gelatin capsules containing temazepam in liquid or semi-solid form have been studied and show faster absorption compared to hard capsules with powder 3, 4, 5. The soft gelatin formulation produces:
- Higher peak plasma concentrations (750 ng/mL vs 587 ng/mL for tablets) 4
- Faster time to peak (approximately 30-40 minutes) 3
- Similar overall bioavailability (AUC) 3
However, the standard U.S. market formulation remains the hard gelatin capsule with powder fill 1.
Clinical Implications
The powder formulation means the capsule should be swallowed whole 1. Unlike sustained-release bead formulations where capsules can sometimes be opened with beads administered intact (as with tamsulosin) 6, temazepam's powder formulation would result in immediate release of the entire dose if opened, potentially altering pharmacokinetics 3, 4.
The bioavailability is dose-proportional: four 7.5 mg capsules are bioequivalent to one 30 mg capsule in terms of extent of absorption, though the smaller capsules reach peak concentration slightly faster 7.