nt: six vessels, paddle or basket, and an acceptance value Q at 30 or 45 minutes — the workhorse of immediate-release QC. Do you stick with 50 rpm, or bump to 75 when the blend gets more hydrophilic with extra PVP?
And i’d stay at 50 rpm and tune the medium first — if the extra PVP slows wetting, try 0.05–0.1% SLS or a slight pH nudge so it stays discriminatory per USP <711>; only move to 75 if you’ve got persistent cone/floating even with sinkers and document it via robustness. FDA’s methods database has precedent: Dissolution Methods — did you see a paddle cone at about 10–15 min, or are we just reaching for 75 as duct tape?
But i think sticking with 50 rpm makes sense, especially for the immediate-release QC test at 30 or 45 minutes. If you’re adjusting with PVP, don’t overlook how surfactants like SLS can really help with wetting issues. Got a specific formulation in mind you’re testing this with?
But when adjusting the blend with PVP, I’ve found that using a slightly higher paddle speed can help ensure consistent results at 30 minutes. It might be worth testing both speeds under the same conditions to see which gives you better dissolution. Have you tried varying the speed on your current setup?