สารบัญ

Thai name  โกฐกะกลิ้ง  (KOT KA-KLING)

Category  Bitter.

        Nux Vomica consists of the dried ripe seeds of Strychnos nux-vomica L. (Family Loganiaceae).  It contains not less than 1.50 per cent for the sum of brucine (C₂₃H₂₆N₂O₄) and strychnine (C₂₁H₂₂N₂O₂),
of which 43 per cent to 67 per cent is strychnine, calculated on the dried basis.

Constituents  Nux Vomica contains alkaloids, predominantly indole alkaloids i.e., strychnine and brucine, are its major components.  It also contains catechol, secoxyloganin and squalene.   

Origin of plant  Nux vomica is native to India, Bangladesh, Sri Lanka, and Southeast Asia.

Description  Odourless; taste, very bitter and persisting. Macroscopical  Discoid, 10 to 30 mm in diameter, 4 to
6 mm thick, with a slightly raised margin, one surface slightly convex, the other one slightly concave, or sometimes irregularly curved, light grey to greenish grey, satiny; one surface bearing hilum at the centre, from which extends a radial ridge ending in a slight protuberance on the edge (the micropyle).  Endosperm abundant, translucent, horny with a disc-shaped cavity in the centre.  Embryo bearing two small thin cordate cotyledons in the central cavity next to micropyle and with a cylindrical radicle.
Microscopical  Powdered drug of the seed shows fragments of outer testa in surface view, fragments of the lignified ridges of the hairs and fragments of outer layer of endosperm.  Outer testa:  cells with enlarged, sclerified, strongly thickened and pitted base, which transformed into curved or straight hairs; hair usually broken, with 7 to 10 lignified ridges and round lignified apex.  Fragments of the lignified ridges of hairs appearing as rods or strips, highly variable in length.  Fragments of Endosperm, numerous, consisting of thick-walled polyhedral cells, some of which containing oil and aleurone grains.  Fragments of outer layer of endosperm, a few; in surface view, polyhedral cells, sometimes associated with the brown pigmented layer of the testa of cells with indistinct wall; in transverse section, elongated cells, sometimes with the pigmented layer and the outer testa.

Other relevant information
     1.  Nux vomica shall be properly processed in order to reduce its toxicity before it is compounded in the pharmaceutical preparation.
     2.  When reducing the drug to a powder, take special precautions in handling.

Packaging and storage  Nux Vomica shall be kept in well-closed containers.

Identification
     A. To 3 g of the powdered drug add 3 mL of ammonia TS and 20 mL of chloroform, macerate for 30 minutes with occasional shaking, and filter.  Remove most of the chloroform from the filtrate by warming on a water-bath, add 5 mL of diluted sulfuric acid (1 in 10), and warm on a water-bath while shaking well until the odour of chloroform is no longer perceptible.  After cooling, filter through a pledget of absorbent cotton, and add 2 mL of nitric acid to 1 mL of the filtrate:  a red colour develops.
     B. To the remaining filtrate obtained in test A add 1 mL of potassium dichromate TS, and allow to stand for 1 hour:  a yellow-red precipitate is produced.  Collect the precipitate by filtration, and wash with 1 mL of water.  Transfer a part of the precipitate to a small test-tube, add 1 mL of water, dissolve by warming, cool, and add 5 drops of sulfuric acid dropwise carefully along the wall of the test-tube:  the layer of sulfuric acid shows a purple colour which turns immediately red to red-brown.
    C.  Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
         Standard solution  Dissolve 10 mg of brucine and 10 mg of strychnine in 10 mL of ethanol.
         Test solution  To 2.0 g of the powdered drug add 20 mL of ethanol (70 per cent), allow to macerate for 15 minutes at room temperature, with stirring, and centrifuge.  Use the supernatant.
         Adsorbent  Silica gel G (TLC or HPTLC plate).
         Mobile phase  Strong ammonia solution, methanol, and dichloromethane (1:5:95); use the lower layer.
         Application  Apply 10 µL (or 5 µL) each of Standard solution and Test solution as bands.
         Development and drying  Allow the solvent front to ascend 15 cm (or 6 cm) above the line of application.  Dry the developed plate in air.
         Detection  Spray the plate with iodoplatinate TS, heat at 105° for 15 minutes and examine immediately under visible light.  Observe the result.
         Results  When examined under visible light, the test solution shows a blue band due to brucine in the lower third and violet band due to strychnine around the middle of the chromatogram, corresponding in R_f to the bands shown by the standard solution. 

Loss on drying  Not more than 10.0 per cent w/w after drying at 105° to constant weight (Appendix 4.15).

Foreign matter  Not more than 1.0 per cent w/w (Appendix 7.2).

Total ash  Not more than 3.0 per cent w/w (Appendix 7.7).

Strychnos ignatii P.J. Bergius  Irregularly shaped seeds, neither discoid nor flattened; when examined the powdered drug under a microscope, sclerified hairs, usually sheared off, not thickened at the base and with walls composed of small, oblique, sclerified strips, tightly fused longitudinally are found. 

Assay  Carry out the test as described in the “Liquid Chromatography” (Appendix 3.5). 
Standard preparation  Dissolve about 10 mg of Brucine RS and 10 mg of Strychnine RS, accurately weighed, in acetonitrile and dilute to 10.0 mL with the same solvent.  Dilute 1.0 mL of the solution to 20.0 mL with Mobile phase A.
Assay preparation  Weigh accurately about 1 g of the powdered Nux Vomica, add 10.0 mL of ethanol (60 per cent).  Boil gently, under a reflux condenser, with stirring.  After 30 minutes, cool and filter into a 20-mL volumetric flask.  Wash the filter with ethanol (60 per cent) and dilute to 20.0 mL with the same solvent.  Dilute 1.0 mL of the solution to 20.0 mL with Mobile phase A.
Mobile phase
    Mobile phase A  Triethylamine, acetonitrile, methanol, tris(hydroxymethyl)-aminomethane buffer solution pH 9.0 (0.1:7.5:7.5:85)
    Mobile phase B  Triethylamine, tris(hydroxymethyl)aminomethane buffer solution pH 9.0, acetonitrile, methanol (0.1:15:42.5:42.5)

The step gradient of mobile phases is as follows:

Chromatographic system
               DETECTOR  Ultraviolet light (260 nm) 
               COLUMN  A stainless steel column (15 cm × 4.6 mm), packed with octadecylsilyl bonded to porous silica or ceramic microparticles (3.5 µm), end-capped with ethylene-bridged hybrid particles containing both inorganic (silica) and organic (organosiloxanes) components.
               COLUMN TEMPERATURE  35°
               FLOW RATE  1.0 mL per minute
System suitability
     Sample  Standard preparation
Suitability requirements
     RESOLUTION  Not less than 3.0 between brucine and strychnine peaks.
     RELATIVE STANDARD DEVIATION  Not more than 2.0 per cent for brucine and for strychnine.
Procedure  Separately inject equal volumes (about 10 mL) of Standard preparation and Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks.  Identify the peaks due to brucine and strychnine in the assay preparation using the retention time of brucine and strychnine in the standard preparation.
Calculation  Calculate the contents of brucine and strychnine, in the portion of the Nux Vomica taken by the expression:

A_uW(2P) /A_sw,

      in which A_u is the area of the peak due to brucine or to strychnine obtained from Assay preparation; A_s is the area of the peak due to brucine or to strychnine obtained from Standard preparation; w is the weight, in g, of Nux Vomica in Assay preparation, W is the weight, in g, of Brucine RS or of Strychnine RS in Standard preparation; P is the declared content of C₂₃H₂₆N₂O₄ in Brucine RS, or C₂₁H₂₂N₂O₂ in Strychnine RS.