I currently take enbrel, and I've experienced a similar effect as you. My enbrel injection wears off a couple of days before my next injection. My doctor gave me the option to up the dose to twice a week (50 mg, not 25 2x), but warned that it does pack a double whammy for the immune system and leaves you at a much higher risk for infection. It's not worth the risk to me. Some weeks are better than others and my injection lasts up to a day before the next injection. On the bad weeks, I just take some tramadol and use lots of hot baths and heating pads. Overall, though, I think enbrel is a great drug.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Early Lupus
Current Meds: Enbrel, Plaquenil, Methotrexate, nexium, tramadol, nasonex,Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan, zyrtec, zegerid, aciphex