Physostigmine salicylate

Physostigmine salicylate Antilirium) Anticholinergics (including tricyclic antidepressants)... 

After a single subcutaneous injection of 1 mg of physostigmine salicylate (equivalent to 0.67 mg base) to one subject, a peak plasma concentration of0.0036 fig/ml was achieved after 15 minutes (R. Whelpton, ibid.). 

After a single oral dose of 4 mg of physostigmine salicylate to one subject, a peak plasma concentration of about 0.001 pg/ml was attained in 0.75 hour(M. Gibson eta/.. Lancet, 1985,1, 695- 96). 

Wells developed a nomogram based on the above equation to readily calculate E values from the MW and Liso value of the drug. Thus, the E value for physostigmine salicylate MW = 413.46) calculated using Liso = 3.4 for a uni-univalent electrolyte is equal to 0.14, which is close to 0.16 E value) in Table 1. This small deviation is attributable to the difference between the experimentally determined Ljso (3.9) of physostigmine salicylate and the theoretical value of 3.4 for a uni-univalent electrolyte. By knowing the E value, the solution can be adjusted to isotonicity as shown below. 

Example 2 Calculate the amount of sodium chloride needed to prepare 100 ml of 2% isotonic physostigmine salicylate solution. 

Example 3 Prepare 100 ml of 2% physostigmine salicylate solution isotonic with blood. 

Using Eq. (20) and E of physostigmine salicylate = 0.16 from Table 1, the volume of water needed to prepare isotonic solution, V = 2g x 0.16 x lll.lml/g = 35.55ml. This solution can be diluted with 64.45 ml of any isotonic diluting solution to obtain 100 ml of 2% isotonic physostigmine salicylate solution. To verify the results, if we assume that we dilute the above solution with 64.45 ml of isotonic sodium chloride solution, the equivalent amount of sodium chloride added is 0.58 g, which matches with results obtained using the class I methods. 

Physostigmine salicylate occurs as a white, shining, odorless cry.stal nr white powder that is soluble in water (l 7S). alcohol (1 16), or chloroform (1 6) but much le.ss soluble in ether (1 2S0). On prolonged exposure to air and light, the... 

Acetylcholine Cl (Miochol) Carbachol intraocular (Miostat) Pilocarpine HCL (Isopto Carpine) Pilocarpine nitrate (Ocusert Pilo-20) Echothiophate iodide (Phospholine Iodide) Physostigmine salicylate (Isopto Eserine) Betaxolol HC1 (Betoptic) Levobunolol HC1 Timolol maleate (Timoptic) Acetazolamide (Diamox) Brinzolamide ophthalmic sus. 1% Dichlorphenamide (Daranide) Dorzolamide (Trusopt) Methazolamide (Neptazane)... 

Physostigmine salicylate in 0.5 % aqueous solution was determined by Teare and Borst by freeze-drying of samples of 0.2 ml, and conversion of the compound into its trimethyl silyl derivative by dissolving the residue in 5 yl of dry pyridine and 10 yl of N,0-bis(trimethyl -silyl)acetamide. The solution was allowed to stand for 1 h before injecting 1.2 yl into the gas chromatograph. A 3.8 % SE-30 on Diatoport S column and a temperature of 145°C was used for the analysis. The physostigmine THS and the salicylic acid TMS derivatives were eluted separately. Routine analysis over several days gave a precision of 11.5 %. 

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