Calcium oxybate magnesium oxybate potassium oxybate and sodium oxybate?

They’re all salts of gamma-hydroxybutyric acid (GHB). The active drug is GHB; the different names just mean different counterions (the salt form) attached to GHB: sodium, potassium, calcium, or magnesium. The salt can affect things like solubility and, in some products, the sodium load.

A quick overview of each in current medical use:
- Sodium oxybate: The best-known clinically used form. Used for narcolepsy (with or without cataplexy) under brand name Xyrem in a restricted-access program. It’s a controlled substance (in the U.S., a Schedule III medication under REMS). Two nighttime doses are common in treatment.
- Calcium oxybate and Magnesium oxybate: These are less commonly used on their own. They exist as salts of GHB, but in practice the approved narcolepsy products use a mixed salt formulation to reduce sodium exposure (see Xywav below).
- Potassium oxybate: Not a widely marketed or standardly used pharmaceutical form. There’s less clinical development or approved product for this specific salt.

Important safety notes:
- All forms are CNS-active and have abuse/dependence potential. They can cause severe sedation, respiratory depression, and coma, especially with alcohol or other depressants.
- They are tightly regulated in many countries. In the U.S., the main narcolepsy products are regulated (Xyrem is sodium oxybate; Xywav is a lower-sodium calcium/magnesium/sodium oxybate mix).

If you meant this in a clinical context (treatment question, regulatory status, or research), tell me what you need specifically and I can tailor the details.