the present inventors have surprisingly found that pyridoxal 5 ′- phosphate is safe and low in side effects at relatively high concentrations , including concentrations previously known to be undesirable for vitamin b6 . the present inventors have found that p5p is thus more tolerable than vitamin b6 and has a much higher dosage requirement to result in toxicity , such as is observed with high doses of vitamin b6 . high doses of p5p is recognized as an improvement in treatment . a phase i , single center , single - dose , open - label , sequential ascending dose study to evaluate the safety and tolerance of pyridoxal - 5 ′- phosphate , in an enteric - coated tablet , following a single dose of 250 mg , 750 mg , 1000 mg , and 4000 mg in healthy subjects under fasting conditions was conducted . a total of 32 healthy , adult subjects signed the study - specific informed consent form and were confined in the clinical study unit ; of these subjects , 24 ( 6 subjects in each dose level ; 3 males and 3 females ) were dosed and were enrolled in the study ; all of these enrolled subjects completed the study . subjects were confined to the sfbc anapharm clinical research facility from at least 12 hours prior to drug administration until after the 24 . 0 - hour post - dose blood draw . subjects enrolled in this study were members of the community at large . subject screening procedures included informed consent , inclusion / exclusion check , demography , medical history , medication history , physical examination , height , weight , body mass index , a concomitant medication check , vital signs measurements ( blood pressure , pulse rate , respiratory rate , and oral temperature ), a 12 - lead electrocardiogram ( ecg ), a urine drug screen , a urine pregnancy test ( female subjects ), hematology , biochemistry , urinalysis , and hiv and hepatitis testing . all participating subjects were judged eligible for the study when assessed against the inclusion and exclusion criteria . all cohorts were sequentially dosed in an ascending fashion . subsequent cohorts were dosed only after the completion of clinical part of the previous cohort and after revision , by the sponsor and the qualified investigator , of the safety data . subjects were administered a single oral dose of study medication , as a 1 × 250 mg ( cohort 1 ), 3 × 250 mg ( cohort 2 ; total dose of 750 mg ), 4 × 250 mg ( cohort 3 ; total dose of 1000 mg ), or 16 × 250 mg ( cohort 4 ; total dose of 4000 mg ) enteric - coated tablets . after a supervised overnight fast of at least 10 hours , subjects were administered the medication as a single oral dose of 1 , 3 , 4 , or 16 enteric - coated tablets containing 250 mg of p5p ( total dose of 250 mg , 750 mg , 1000 mg , or 4000 mg ), with 300 ml of water . subjects were dosed as specified in the protocol , and subsequently fasted for at least 4 hours . subjects in cohorts 2 to 4 did not receive their dose until the clinical part of the preceding dose level was completed , the safety data reviewed by the principal investigator and the sponsor , and a decision taken to proceed or not with the next dose level . clinical laboratory tests ( hematology , biochemistry , and urinalysis ) were performed for each subject at the time of the screening and post - study procedures and prior to dosing . the pharmacokinetic parameters to determine bioavailability for this study were : area under the concentration - time curve from time zero to time of last non - zero concentration ( auc 0 - t ), maximum observed concentration ( c max ), time of observed c max ( t max ) and elimination half - life ( equivalent to t 1 / 2 ). p5p produced optimal effects when administered at 250 mg likely due to a directly proportional relationship between the dose administered and the variability of plasma p5p concentrations achieved in a subject ( table 1 ), most likely due to unknown enzymatic activities . all of the patients proceeded to the highest dosage form , and none of the patients presented any significant side effects or evidence of toxicity . thus p5p was found to be well tolerated in patients in dosages up to 4000 mg . human males aged between 65 and 90 are separated into four random groups : control , low dose of p5p ( 100 mg / day ), medium dose of p5p ( 250 mg / day ), and high dose of p5p ( 750 mg / day ). all dosages are administered orally for 3 weeks before subjecting the patients to an associative learning task . the patients are subjected to an associative learning task , as follows . briefly , patients are comfortably seated in front of a computer . patients are asked to learn the associations between six colors and the numbers 1 - 6 , using trial and error . subjects are then required to recall this association , a defined period of time after the associations are learned . tests are repeated , with the defined period of time increasing , until the patients are no longer able to associate the colors with the numbers . patients receiving p5p are able to recall the association between the numbers and the colors a significantly longer time after the association is made , as compared to control patients . further , though there is no significant difference in associative learning and memory between the medium and high dose groups , there is significant difference between the low group and these two groups . thus the low dose group exhibits improved information storage and retrieval than the control group , and the medium and high dose groups exhibits improved information storage and retrieval over the low dose group . individuals diagnosed with mild depression are divided into four groups at random : control , low dose of p5p ( 100 mg / day ), medium dose of p5p ( 250 mg / day ), and high dose of p5p ( 750 mg / day ). all dosages are administered orally for 3 weeks . the level of depression of the individuals is assessed , both before , and after treatment , using conventional methodologies . these include completion of several depression inventory questionnaire scales including the cornell scale for depression in dementia , centre for epidemiologic studies depression scale , the geriatric depression scale ( short version ), beck depression inventory and the zung self - rating depression scale as well as diagnosis by a trained professional according to the dsm - iv . these questionnaires measure depression through questions related to appetite , sadness , worthlessness / inadequacy , concentration , exhaustion , failure , retardation , socialization , isolation , anxiety , irritability , agitation , loss of interest , lack of energy , diurnal mood variation , insomnia , suicidal thoughts , low self - esteem , pessimism , mood congruent delusions , satisfaction , withdrawal , fulfillment , mood , fear , guilt , self - accusations , somatic preoccupation and loss of libido . patients given p5p are significantly less depressed than control individuals . patients in the medium and high dose groups are significantly less depressed than patients in the low dose group . patients in the medium and high dose groups are not significantly different .
this invention relates to improvement of mood , memory and cognitive function with administration of pyridoxal 5 ′- phosphate . also provided is the use of pyridoxal 5 ′- phosphate for the preparation of a medicament for the improvement of mood , memory and cognitive function , and kits comprising pyridoxal 5 ′- phosphate for the same purpose .