Differences between Hydrocodone and Oxycodone
Contents
Hydrocodone vs. oxycodone
Hydrocodone and oxycodone are semi-synthetic opioid analgesics prescribed for the management of moderate to severe pain. While both drugs are derived from alkaloid compounds found in the opium poppy (Papaver somniferum), they possess distinct chemical structures and metabolic pathways. Hydrocodone is typically synthesized from codeine, whereas oxycodone is synthesized from thebaine. Both substances function by binding to mu-opioid receptors in the central nervous system to alter the perception of and emotional response to pain.[1]
Comparison table
| Category | Hydrocodone | Oxycodone |
|---|---|---|
| Chemical precursor | Codeine (primarily) | Thebaine |
| Potency ratio | 1:1 with oral morphine | 1.5:1 with oral morphine |
| DEA schedule | Schedule II | Schedule II |
| Common combinations | Acetaminophen (paracetamol), ibuprofen | Acetaminophen, aspirin, naloxone |
| Metabolism | Primarily CYP2D6 and CYP3A4 | Primarily CYP3A4 and CYP2D6 |
| Available forms | Tablet, capsule, oral solution | Tablet, capsule, solution, injection |
| Common side effects | Stomach pain, constipation, dry mouth | Constipation, itching, drowsiness |
Clinical efficacy and metabolism
Medical professionals evaluate the strength of these opioids using morphine milligram equivalents (MME). Oxycodone is generally considered more potent than hydrocodone. Clinical studies indicate that 5 mg of oral oxycodone is approximately equivalent to 7.5 mg of oral hydrocodone. Despite this difference in potency, both drugs provide similar levels of analgesia when dosages are adjusted correctly.
Metabolism occurs primarily in the liver. Hydrocodone is converted into its more active metabolite, hydromorphone, by the cytochrome P450 enzyme CYP2D6. Oxycodone is metabolized into oxymorphone via the same enzyme, although its primary metabolic pathway involves CYP3A4, which produces noroxycodone. Because of these enzymatic requirements, patients with specific genetic variations in CYP2D6 may experience different levels of pain relief or side effects from these medications.[2]
Adverse effects and safety
The side effect profiles of both medications include respiratory depression, sedation, and physical dependence. Common gastrointestinal issues include nausea and constipation. Some clinical observations suggest that oxycodone is associated with a higher incidence of pruritus (itching) and constipation compared to hydrocodone. Conversely, hydrocodone users sometimes report higher rates of non-specific stomach pain.
Both medications carry a high risk for misuse and substance use disorder. Overdose from either substance can be fatal, often due to respiratory arrest. The presence of other central nervous system depressants, such as alcohol or benzodiazepines, increases the risk of serious complications.
Legal status and regulation
In the United States, the Drug Enforcement Administration (DEA) classifies both hydrocodone and oxycodone as Schedule II controlled substances. This classification indicates that the drugs have a high potential for abuse but possess currently accepted medical uses. Until 2014, hydrocodone combination products (such as those containing acetaminophen) were classified as Schedule III. The DEA reclassified these products to Schedule II to implement stricter controls on prescriptions, such as prohibiting refills without a new written order from a physician.[3]
