Do you use ideal body weight, adjusted body weight, or actual weight when dosing medications for patients with AKI on CRRT?

There is no single body weight metric that applies to all drugs in patients on CRRT. The choice depends on the drug's pharmacokinetic properties (hydrophilic vs. lipophilic, volume of distribution) and on whether a loading or maintenance dose is being calculated. Loading doses are driven by the volume of distribution, and maintenance doses are driven by CRRT clearance, non-renal clearance, and residual renal clearance. In short, the answer is drug-specific.