Oxycodone IR and Oxycodone HCl: Understanding the Terminology
Yes, "oxy IR" (oxycodone immediate release) and "oxy HCl" (oxycodone hydrochloride) refer to the same medication—they are simply different ways of describing oxycodone in its immediate-release salt form. 1
Chemical and Pharmaceutical Nomenclature
Oxycodone hydrochloride (HCl) is the chemical salt form in which oxycodone is manufactured and dispensed in virtually all pharmaceutical preparations 1, 2
The "IR" designation refers to the release mechanism (immediate-release), distinguishing it from extended-release (ER) or controlled-release (CR) formulations 3
When prescribers or pharmacists say "oxycodone HCl," they are specifying the salt form, while "oxycodone IR" emphasizes the rapid-onset formulation 1, 4
Practical Clinical Distinctions
The key distinction you need to understand is between immediate-release versus extended-release formulations, not the salt form:
Immediate-release oxycodone HCl has an onset of action within 10-30 minutes and duration of 3-6 hours 3, 1
Extended-release oxycodone HCl (OxyContin CR) has onset around 1 hour and duration of 10-12 hours 3, 2
Both formulations contain the same active ingredient—oxycodone hydrochloride—but differ in their absorption kinetics 4, 5
Bioavailability and Pharmacokinetics
Oral bioavailability of oxycodone HCl ranges from 60-87%, which is higher than most other oral opioids due to lower first-pass metabolism 1, 2
Plasma protein binding is approximately 45%, and the volume of distribution is 2.6 L/kg 1
Plasma half-life is 3-5 hours for immediate-release formulations, with stable plasma levels reached within 24 hours 2, 4
Common Pitfall to Avoid
Do not confuse oxycodone HCl with oxymorphone—these are different medications. Oxymorphone is a metabolite of oxycodone formed through O-demethylation via CYP2D6, and it is also available as a separate immediate-release opioid formulation 3, 1
Prescribing Considerations
When writing prescriptions, specify both the release mechanism (IR vs ER) and the dose to avoid confusion 3
Immediate-release oxycodone HCl is available as tablets, capsules, and oral solution, all containing the same hydrochloride salt 1, 6
The CDC recommends initiating opioid therapy with immediate-release formulations rather than extended-release products 3
For opioid-naïve patients, start with oxycodone IR 5-10 mg every 4-6 hours as needed 7