Oval white pill with letters ri80?

I am aware this is an old post, but for future reference, meaning it may help someone else in the future.
Just click on the link provided by Drugs.com in order to access an image of the pill and also important information:

https://www.drugs.com/imprints.php?imprint=R180&color=&shape=0

I must agree with bucky 1 here i keep coming up with the same thing when i research it.

could be this;
R180
Pill imprint R180 has been identified as Tizanidine 4 mg.

Tizanidine is used in the treatment of muscle spasm; cluster headaches and belongs to the drug class skeletal muscle relaxants. Risk cannot be ruled out during pregnancy. Tizanidine 4 mg is not subject to the Controlled Substances ActTreating muscle spasms. It may also be used for other conditions as determined by your doctor.Seek medical attention right away if any of these SEVERE side effects occur: Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); change in emotions, mood, or behavior; hallucinations; increased muscle spasms; muscle weakness; slow heartbeat; trouble urinating or lack of bladder control; urinary tract infection; yellowing of the skin or eyes.

I would either take it across to the pharmacy for identification or destroy it, please it is not recommended to use/take unidentified meds, hope this helps?