Here you can select doses by dividing your LD50 ie 2000 mg/kg with 5, 10 and 20 resultant doses are 100, 200 and 400 mg/kg

1000, 100, 10 mg/kg.

Just pick three points on a standard logarithmic scale. If the activity needs to be higher to establish practicality then go lower on the scale. 100, 10 and 1 might be more useful.

1. First of all collect the previously published references in such plants or such family. Take the idea from those paper for the appropriate dose.

2. If available human data would be more impressive so that you can correlate the human dose and with rat. 

3. Then chose the optimal dose (eg 300 mg/Kg) then you can calculate the other dose by half or double 

4. If not you have to perform the screening either in vivo or vitro with several doses.

As per Eric and Bhakta,

You may consider three doses as per the availability of the data in literature survey or three points on standard logarithmic curves would be useful.

I would like to add here that the dose of extract administered to the animals should not go beyond 1000 mg/kg. You may use three doses as 500, 50 and 5 mg/kg etc. Also if no efficacy is found you may increase the upper dose.

Dear Nanthini Uma,

I support Bhakta Prasad Gaire.

My recommendation is to make a suitable initial dose first. Take it as standard, then multiple it with the rats body weight as 1x, 2x.

my sugessting dose adjustments are: 0.5x, 1x and 2x dose. here x= variable in accordance with sample extract and its acute toxicity studies.

From your provided info I can suggest to take as, x=750mg/kg bw of rat

Agree with the suggestion of Eric, Bhakta as well as Arjyabrata. My suggestion will be not to go beyond 200mg/kg dose as doses higher than this may give you false +ve results.

I HAVE READ ALL THE SUGGESTION. EVERY BODY SHARES BEST AT HIS / HER LEVEL.

BUT ONE THING IS LEFT BEFORE CHOOSING ANY DOSE OF EXTRACT FOR ANY FOR ANIMAL ADMINISTRATION, IT IS STRICTLY RECOMMENDED THAT INITIALLY YOU HAVE TO PERFORM TOXICITY STUDIES OF THE EXTRACT AT DIFFERENT DOSES. FOR EXAMPLE FROM 100MG/KG TO 1000MG/KG. CALCULATE LD50. AFTER MAKE ASSURANCE OF SAFER RANGE OF DOSES. THEN YOU ARE ALLOWING TO PERFORM BIOLOGICAL ACTIVITIES AT THESE DOSES. REMEMBER, MOST OF THE GOOD JOURNALS REQUIRED TOXICITY STUIES WITH BIOLOGICAL STUDIES. IF ANY DOSE WHICH IS GIVING GOOD /EXCELLANT BIOLOGICAL ACTIVITY IS TOXIC NOT ACCEPTABLE FOR ANIMAL AND OBVIOUSLY FOR HUMAN.

I AM SENDING YOU MY ARTICLES REGARDING ACUTE TOXICITY EXAMINATION

REGARDS

Article Acute Systemic Toxicity of Four Mimosaceous Plants Leaves in Mice

KINDLY RECEIVE SECOND ONE AND READ BOTH OF THE ARTICLES CAREFULLY.

Article Toxicity assessment of Mucuna pruriens Linn seeds.

It must be based on an acute toxicity test result

If you have the therapeutic plasma concentration you can calculate the dose based on the blood volume of the rat. Usually uses a low (half dose), medium and high dose (double dose).

Did you obtain any information on non-lethal effects from your acute toxicity study? For regulatory purposes, ideally your highest dose should be a dose at which some measurable effect, although not necessarily an adverse effect, is apparent. Examples of such a change are a moderate change in food consumption, a moderate by measurable change in behaviour (sedation?), or a histological change that was not associated with overt clinical signs of illness. Then select your medium and low doses using an approximation of the natural logarithm, so that if your top dose is 1000 mg/kg then your other doses  would be 300 and 100 mg/kg.

I think the low dosage should over the least effect dosage, the highest must less than the toxic dosage, and if you experience the pharmacodynamics, I thank you can try the low dosage corresponding to the needing of pharmacokinetics that is 7 dots being the least demands of software processing.

For regulatory purposes you want to identify an NOEL.

Here you can select doses by dividing your LD50 ie 2000 mg/kg with 5, 10 and 20 resultant doses are 100, 200 and 400 mg/kg

In my opinion, if you are trying to see a nice D-R curve you must consider the enzyme kinetics, accordingly you should use M and logaritmic increases (e.g., 100 nM, 316 nM, 1000 nM, 3160 nM, etc.).

I carried out membrane stabilizing test on my plant extract using heat induce hemolysis method. But i discovered that after centrifuging the heated and control samples, the control supernantants colors (containing erythrocyte + Normal saline as well as erythrocyte + Phosphate buffer saline respectively) were completely cleared compared to those of the test groups (extract, indomethacin and prednisolone). The optical density of the controls were also about 10-fold lower than the test groups. Why this difference in absorbance? Don’t hemolysis ought to occur more in heated control samples? Please help me out. Your comments would be very useful. Please download the attached file for further explanations.

Thanks