Ipecac
»Ipecac consists of the dried rhizome and roots of Cephaëlis acuminataKarsten,or of Cephaëlis ipecacuanha(Brotero)A.Richard (Fam.Rubiaceae).
Ipecac yields not less than 2.0percent of the total ether-soluble alkaloids of ipecac.Its content of emetine (C29H40N2O4)and cephaeline (C28H38N2O4)together is not less than 90.0percent of the amount of the total ether-soluble alkaloids.The content of cephaeline varies from an amount equal to,to an amount not more than 2.5times,the content of emetine.
Botanic characteristics— Amixture of segments of the roots and rhizomes.The root segments are mostly curved and flexuous,occasionally branched,up to 15cm in length and usually from 3to 6.5mm in diameter,but may be up to 9mm in diameter,grayish,grayish brown,or reddish brown,the reddish brown type often having light-colored abrasions,transverse ridges about 0.5to 1.0mm wide that extend about halfway around the circumference of the root and fade at their tapering extremities into the general surface,with from 1to 6of these ridges per cm,and annulations sometimes seen at irregular intervals.The rhizomes are cylindrical,about 2mm thick,finely longitudinally wrinkled,with a few elliptical scars.The odor is distinctive;the dust is sternutatory.
Histology— At the center of the root is a well-defined primary xylem but no pith.Surrounding this is a dense wood of secondary xylem crossed by medullary rays.These elements are all lignified.External to the wood is a narrow band of secondary phloem and a wide parenchymatous phelloderm surrounded by a narrow layer of cork a few cells thick.The secondary xylem consists of narrow,bordered-pitted tracheidal vessels and tracheids in combination with xylem parenchyma.The latter have simple pits and contain starch grains.Starch is present also in the medullary rays.The phloem occurs as small groups of sieve tissue embedded in parenchyma.The wide phelloderm consists of round-celled cellulose parenchyma filled with starch grains and a few idioblasts,each of which contains a bundle of acicular raphides of calcium oxalate crystals about 30to 80µm long.The starch grains are rarely single but usually occur as 2to 4and sometimes 8in a clump.Individual grains measure up to 22µm in diameter.
The rhizome differs from the root in having a ring of xylem around a large pith.The pericycle contains characteristic sclerenchymatous cells.Spiral vessels are found in the protoxylem.The pith is composed of pitted parenchyma,which is somewhat lignified.
Overground stems— The proportion of overground stems does not exceed 5%.
Foreign organic matter á561ñ— The proportion of foreign organic matter does not exceed 2.0%.
Assay for total ether-soluble alkaloids— [NOTE—It is important that the ether used in this assay shall have been shown by test to be free from peroxides within 24hours prior to use.]The alkaloids may be extracted by either of the methods given in the following two paragraphs.
I— To 10g of finely powdered Ipecac,in a suitable container,add 100mLof ether,accurately measured at 25,insert the stopper in the container tightly,shake the mixture thoroughly,and allow it to stand for 5minutes.Then add 10mLof 6Nammonium hydroxide,close again tightly,shake it for 1hour in a mechanical shaker or intermittently during 2hours,and allow to stand overnight at a temperature not exceeding 25.Again shake the mixture intermittently during 30minutes,and allow the drug to settle at 25.Transfer to a separator a 50.0-mLaliquot of the clear,supernatant,representing 5g of Ipecac.
II— Place 5g of the finely powdered Ipecac in a continuous-extraction thimble.Add enough ether to cover the powder,and allow to stand for 10minutes with occasional stirring.Add 3mLof ammonium hydroxide,mix,and allow to stand overnight.Cover the drug with a pledget of cotton,pack well,and extract with ether for 5hours.Transfer the ether extract to a separator.
Extract the alkaloids from the ether with 2Nsulfuric acid,using at first 15mL,or more,if necessary,to ensure an acid reaction,then successive 10-mLportions until extraction is complete,and filtering all extracts through the same filter into a second separator.To the combined acid solutions add about an equal volume of ether,render the mixture distinctly alkaline with 6Nammonium hydroxide (at least pH10,by test paper),and extract with successive portions of ether until the last extract shows not more than a slight turbidity when treated as follows:Evaporate 1mLof the last extraction,dissolve the residue in 0.5mLof 0.5Nhydrochloric acid,and add 1drop of mercuric iodide TS.
Filter each portion of the ether extract into a flask or beaker,and carefully evaporate the combined ether extracts on a steam bath almost to dryness.Add 5mLof ether and 10.0mLof 0.1Nsulfuric acid VS,and heat on a steam bath to effect complete solution of the alkaloids,and to remove all the ether.Cool,add 15mLof water,then add methyl red TS,and titrate the excess acid with 0.1Nsodium hydroxide VS.Each mLof 0.1Nsulfuric acid is equivalent to 24.0mg of the total ether-soluble alkaloids of ipecac,calculated as emetine (C29H40N2O4).
Assay for emetine and cephaeline—
Standard preparation— Weigh accurately a suitable quantity of USP Emetine Hydrochloride RS,and dissolve in 0.5Nsulfuric acid.Dilute quantitatively and stepwise with the same dilute sulfuric acid to obtain a solution having a known concentration equivalent to about 50µg of emetine per mL.
Assay preparation— Prepare a test sampleas directed under Articles of Botanical Origin—Methods of Analysis á561ñ.Transfer to a 150-mLbeaker about 200mg,accurately weighed,of the fine powder.Add 2mLof methyl sulfoxide,mix with a flattened stirring rod to assure complete wetting of the powder,and allow to stand for about 30minutes.Add 2mLof water and about 1g of sodium bicarbonate,and mix.
Phosphate buffer— Prepare approximately 0.5Msolutions of monobasic potassium phosphate (containing 5.1g per 75mL)and dibasic potassium phosphate (containing 2.2g per 25mL).Mix 3volumes of 0.5Mmonobasic potassium phosphate with 1volume of 0.5Mdibasic potassium phosphate,and adjust by the addition of one or the other of the solutions to a pHof 6.0±0.05.Dissolve 7.5g of potassium chloride in 100mLof the resulting solution.
Citric acid buffer— Prepare approximately 0.5Msolutions of sodium citrate (containing 6.5g per 50mL)and citric acid (containing 4.8g per 50mL).Mix equal volumes of these solutions,and adjust by addition of one or the other of the solutions to a pHof 4.0±0.05.
Chromatographic columns— For each column,pack a pledget of fine glass wool in the base of a chromatographic tube (25-×200-mm test tube to which is fused a 5-cm length of 7-mm tubing)with the aid of a tamping rod having a disk with a diameter about 1mm less than that of the tube.
Prepare Column Ias follows.To the Assay preparationadd 6g of purified siliceous earth,mix,transfer the mixture to the column,scrub the beaker with about 1g of the purified siliceous earth,transfer this to the top of the column,and tamp.Prepare Column IIusing 3g of the purified siliceous earth and 2mLof Phosphate buffer;prepare Column IIIusing 2mLof Citric acid bufferand 3g of the purified siliceous earth;and prepare Column IVusing 2mLof sodium hydroxide solution (1in 50)and 3g of the purified siliceous earth.Pack a pledget of glass wool on the top of each column.
Procedure— [NOTES—Use water-saturated solvents throughout this procedure.Rinse the tips of the chromatographic columns before discarding them.]Mount Columns Iand IIso that the effluent from Column Iflows onto Column II.Pass three 50-mLportions of ether through the columns,and discard Column Iand the eluate.Mount Column IIIbelow Column IIand pass three 50-mLportions of a mixture of 1volume of ether and 3volumes of chloroform through the columns.Discard Column IIand the eluate.Wash Column IIIwith 25mLof the ether-chloroform mixture,followed by 25mLof a mixture of equal volumes of ether and isooctane,and discard the washings.Wash Column IVwith 20mLof a 1in 50solution of triethylamine in the ether-isooctane mixture,and discard the washing.Mount Column IVbelow Column III,and place as a receiver under Column IVa 125-mLseparator containing 15mLof 4Nsulfuric acid.Pass through the columns 10mLof a 1in 5solution of triethylamine in the ether-isooctane mixture,followed by three 10-mLportions of a 1in 50solution of triethylamine in the ether-isooctane mixture.Discard Column III,and pass through Column IV20mLof the 1in 50solution of triethylamine in the ether-isooctane mixture.Shake the separator,allow the phases to separate,and transfer the aqueous extract to a 50-mLvolumetric flask.Extract with two additional 10-mLportions of 0.5Nsulfuric acid,combining the extracts in the volumetric flask.Add 0.5Nsulfuric acid to volume,and mix (emetine solution).
Elute Column IVwith 75mLof chloroform,collecting the eluate in a 250-mLseparator containing 150mLof ether.Discard Column IV.Extract with one 20-mL,and then with two 10-mL,portions of 0.5Nsulfuric acid,collecting the extracts in a 50-mLvolumetric flask.Rinse the stem of the separator,add the acid to volume,and mix (cephaeline solution).
Concomitantly determine the absorbances of the emetine solution,the cephaeline solution,and the Standard preparationin 1-cm cells at the wavelength of maximum absorbance at about 283nm and at 350nm,with a suitable spectrophotometer,using 0.5Nsulfuric acid as the blank.
Calculate the quantity,in mg,of emetine in the portion of Ipecac taken by the formula:
0.05C(A283-A350)U/(A283-A350)S,
in which Cis the concentration,in µg per mL,of emetine in the Standard preparation,and the parenthetic expressions are the differences in the absorbances of the solution of emetinefrom the Assay preparation(U)and the Standard preparation(S),respectively,at the wavelengths indicated by the subscripts.
Calculate the quantity,in mg,of cephaeline in the portion of Ipecac taken by the formula:
0.971(0.05C)(A283-A350)U/(A283-A350)S,
in which 0.971is the ratio of the molecular weight of cephaeline to that of emetine,Cis as defined in the preceding paragraph,and the parenthetic expressions are the differences in the absorbances of the solution of cephaelinefrom the Assay preparation(U)and the Standard preparation(S),respectively,at the wavelengths indicated by the subscripts.
Auxiliary Information— Staff Liaison:Gabriel I.Giancaspro,Ph.D.,Senior Scientist and Latin American Specialist
Expert Committee:(DSB)Dietary Supplements:Botanicals
USP28–NF23Page 1058
Pharmacopeial Forum:Volume No.30(3)Page 866
Phone Number:1-301-816-8343