how long does keppra stay in your system? how about the generic

Hi BrDietrich, My last test was in April of this year (2012), with a Keppra (Levetiractam) level of 18 µg/mL. The test was listed as performed at ARUP Laboratory, Salt Lake City, Utah, and it listed their Reference Range as 5 to 30 µg/mL, with the added "interpretive information" note, of: "The proposed therapeutic range for seizure control is 5-30 µg/mL. Pharmacokinetics of levetiracetam are affected by renal function. The relationship between serum concentration and toxicity is not known." My blood was drawn at 09:05 AM, about 8 hours after a midnight/early-morning dose totaling 1000 mg of Keppra in tablets at 01:00 AM. The previous dosage was 1500 mg 25 hours earlier than the 01:00 AM dose (I was reducing Keppra intake back to residual levels after a day of clusters a couple days earlier, and the test matched mid-range for ARUP's Reference Range). Other blood tests the same day required fasting, so I hadn't any food or further liquids after taking the 01:00 AM Keppra dose, and the walk to the clinic's blood lab was 1.2 miles, so, also, the reading was probably increased somewhat by the exercise and initial Stage III chronic kidney disease, with my being 59 years old. While all the medical groups can't establish a valid "proposed therapeutic/reference range" for levetiracetam levels in mutual agreement, epilepsy's rather subjective response seems the more objective. Wading through the various numbers involving "69 epileptic patients treated with 500 to 3000 mg/d of levetiracetam [with ranging] from 1.1 to 33.5 [µg/mL],": "Good?" Responders had levetiracetam plasma concentrations of 4.6 to 21 µg/mL (with a mean of 12.9 µg/mL), but, The Non--Responders had levetiracetam plasma concentrations of 1.1 to 20.9 µg/mL (with a mean of 9.5 µg/mL). "Nevertheless, the levetiracetam plasma concentration could be used to help clinicians detect severe intoxication or to verify compliance by repeating the measurement in patients." http://www.ncbi.nlm.nih.gov/pubmed/17898647 A Medical Group's checking for mandatory satisfaction of such fickle "compliance" ranges seems like something somewhat removed from considering any self-evaluation of therapeutic benefits of a medical regimen, and more like a Catch-22 corporate medical group's attempt at hierarchy economics. With views of "Therapeutic drug monitoring: not needed", slightly older therapeutic ranges (2005) included "6-20 mg/L (35-120 µmol/L)" http://www.ncbi.nlm.nih.gov/books/NBK2597/#ch14.s68 Previously, a clinic continued to demand the economics from generic versions of Dilantin in stopping my grand mal seizures, but the wide variances of different batches of generics often resulted in ambulance trips to ER over about a two year period after emergency surgery by a neurosurgeon, when the clinic finally stopped blaming me for "non-compliance" and filed an "e-TAR" authorizing brand name Dilantin to save sub-contractors money on ambulance trips. Dilantin and osteoporosis with the economics of Boniva versus clinic denial of their own tests were then the next elements of a Catch-22 with the pharmacy therapeutics involving epilepsy. References to the presently most recognized "reference range" of 12-46 mg/L is given in the footnotes to "From evaluation of 470 patients in a specialty epilepsy clinic, a reference range of 12–46 mg/L has been proposed [47]...Other than to evaluate potential toxicity or to assess compliance, the value of TDM for levetiracetam is mostly in adjusting dosage for renal insufficiency [120]." in "Therapeutic Drug Monitoring of the Newer Anti-Epilepsy Medications" by Matthew D. Krasowski, at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904466/ (All the newer measurement techniques are looking for a use too???: "Multiple analytical methodologies have been reported for the measurement of levetiracetam in plasma/serum including HPLC [112, 113], GC [114, 115], GC/MS [116], LC/MS/MS [117], microemulsion electrokinetic chromatography [118] and capillary electrophoresis [119]." [47. Leppik, I.E.; Rarick, J.O.; Walczak, T.S.; Tran, T.A.; White, J.R.; Gumnit, R.J. Effective levetiracetam doses and serum concentrations: Age effects. Epilepsia 2002, 43, 240.] currently (September 24, 2012) at, when not "locked": Epilepsia, Volume 43, Issue Supplement s7, page 240: http://onlinelibrary.wiley.com/doi/10.1046/j.1528-1157.43.s7.1.x/pdf (3.1 MB file size) with the "Conclusions: The mean dose of LEV in this population was ~2,500 mg/day, but the range was large. Although females received lower daily doses, their doses were higher than males on a mg/kg basis. The apparent clearance was greatest in persons younger than 18 years and lowest in in those older than 65 (~26% greater). It appears the concentrations of 29 µg/ml with 1 SD of 17.2 are associated with the highest doses attained in a clinical setting, and thus a range of 12–46 µg/ml could be considered effective for most persons with epilepsy. (Supported by MINCEP Epilepsy Care.)" "MINCEP,12 the epilepsy care research group, proposed a reference range of 12---46 mg/l (70---270 µmol/l) for levetiracetam. The lower limit of this interval was validated by Lancelin et al.13 [13 http://www.ncbi.nlm.nih.gov/pubmed/17898647 again] in a study of 69 patients carried out in 2007." "Pharmacokinetic Monitoring of Antiepileptic Drugs" by A. Aldaz, et al. (Farm Hosp. 2011;xxx(xx):xxx---xxx), page 3 at: http://www.elsevier.es/sites/default/files/elsevier/eop/S2173-5085(11)00028-1.pdf I tend to like many of sentences from Emilio Perucca in "The Treatment of Epilepsy", Simon D. Shorvon (Editor), Emilio Perucca (Editor), Jerome Engel Jr. (Editor), (2009): http://books.google.com/books?id=rFFzFzZJtasC&pg=PA559&lpg=PA559&dq=levetiracetam+reference+range+12-46&source=bl&ots=KnVPt2ZYA3&sig=0X2s0nasxjsJj3FcsOWA7quUR08&hl=en&sa=X&ei=WX9fULyTNuKliQLl4oGIBA&ved=0CCoQ6AEwAg#v=onepage&q=levetiracetam%20reference%20range%2012-46&f=false and, http://books.google.com/books?id=rFFzFzZJtasC&pg=PA559&lpg=PA559&dq=levetiracetam+reference+range+12-46&source=bl&ots=KnVPt2ZYA3&sig=0X2s0nasxjsJj3FcsOWA7quUR08&hl=en&sa=X&ei=WX9fULyTNuKliQLl4oGIBA&ved=0CCoQ6AEwAg#v=onepage&q=primary%20objective%20of%20treatment%20aims%20reduction&f=false page 133 (and page 121), therapeutic range versus reference range...page 121: "The primary objective of treatment aims for complete seizure control, .... but, this, however, should not be achieved at all costs." "The situation should never arise where a patient is made to suffer more from the adverse effects of treatment than from the symptoms of the disease [4]." [4]: "Overtreatment In Epilepsy" (below) "Assessing the most disabling seizure types can require assistance from an external observer, but the patient's perceptions are more important." page 137: "Physicians must always remember that the priority aim of therapy is to treat a patient and not a laboratory value." http://adisonline.com/cnsdrugs/Abstract/2005/19110/Overtreatment_in_Epilepsy__How_It_Occurs_and_How.1.aspx http://www.youtube.com/watch?v=Ax6xr2B5W-I (Amazon-dot-com often has a preview of some of the pages with a search in the book for key word phrases for more pages). (The same Emilio Perucca now President Elect of the ILAE??? http://www.thelancet.com/journals/laneur/article/PIIS1474-4422(12)70196-5/fulltext#article_upsell ). Tadzio