Drug molecules have included stable heavy isotopes of carbon, hydrogen, and other elements, mostly as tracers for quantitation during the drug development process. Due to its potential to alter the pharmacokinetic and metabolic profiles of medications, deuteration has drawn attention[1].

Medication Use During Pregnancy and Lactation ◉ Overview of Medication Use During Lactation
Since erythromycin is present in low concentrations in breast milk and can be safely administered directly to infants, it is safe for breastfeeding women to use. The small amount of erythromycin in breast milk is unlikely to have adverse effects on the infant. Close monitoring of the infant's irritability and potential effects on the gut microbiota, such as diarrhea, candidiasis (thrush, diaper rash), is necessary. One case report and unconfirmed epidemiological evidence suggest that erythromycin use by the mother during the first two weeks of breastfeeding may lead to hypertrophic pyloric stenosis in the infant; however, even if it occurs, the frequency is extremely low, and this association has been questioned.
Topical application for acne treatment is unlikely to cause side effects in the infant, but topical application to the nipples may increase the risk of diarrhea in the infant. Only water-soluble creams or gels should be applied to the breasts, as ointments may expose the infant to high concentrations of mineral oil through licking. [1]
◉ Effects on breastfed infants
A 3-week-old infant was reported to have pyloric stenosis, vomiting, sedation, poor sucking, and slow weight gain, symptoms that may be related to erythromycin in breast milk. [4]
A cohort study of infants diagnosed with hypertrophic pyloric stenosis found that mothers of affected infants were 2.3 to 3 times more likely to have taken macrolide antibiotics within 90 days postpartum than other infants. Stratified analysis of the infants showed an odds ratio of 10 for female infants and 2 for male infants. All affected infants were breastfed. 72% of macrolide prescriptions were erythromycin. However, the authors did not specify which macrolide antibiotics the affected infants' mothers took. [5] A study comparing infants breastfed by mothers taking amoxicillin with infants breastfed by mothers taking macrolide antibiotics found no cases of pyloric stenosis in either group. However, most infants exposed to macrolide antibiotics through breast milk were exposed to roxithromycin. Of the 55 infants exposed to macrolide antibiotics, only 2 had been exposed to erythromycin. 12.7% of the infants exposed to macrolide antibiotics experienced adverse reactions, a rate similar to that of infants exposed to amoxicillin. Adverse reactions included rash, diarrhea, loss of appetite, and lethargy. [6]
A retrospective database study in Denmark analyzed 15 years of data and found that infants born to mothers who took macrolide antibiotics in the first 13 days postpartum had a 3.5-fold increased risk of neonatal hypertrophic pyloric stenosis, but this was not observed after subsequent use. The proportion of breastfed infants is unknown, but likely high. The proportion of women taking each macrolide antibiotic was also not reported. [7]
In a telephone follow-up study, of the 17 infants whose mothers took erythromycin while breastfeeding, 2 infants experienced diarrhea and 2 infants experienced irritability. None of the reactions required medical attention. [8]
Two meta-analyses failed to confirm an association between maternal use of macrolide antibiotics during lactation and hypertrophic pyloric stenosis in infants. [9][10]
◉ Effects on lactation and breast milk
No relevant published information was found as of the revision date.

[1]. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019 Feb;53(2):211-216.

[2]. Erythromycin. Med Clin North Am. 1982 Jan;66(1):79-89.

[3]. Activity of azithromycin or erythromycin in combination with antimalarial drugs against multidrug-resistant Plasmodium falciparum in vitro. Acta Trop. 2006 Dec;100(3):185-91. Epub 2006 Nov 28.

[4]. Antitumor effect of erythromycin in mice. Chemotherapy. 1995 Jan-Feb. 41(1):59-69.

[5]. Neuroprotective effects of erythromycin on cerebral ischemia reperfusion-injury and cell viability after oxygen-glucose deprivation in cultured neuronal cells. Brain Res. 2014 Nov 7. 1588:159-67.

See also: Erythromycin (note moved to).

C37H64D3NO13

737.48

959119-26-7

Erythromycin;114-07-8

3255

White to off-white solid powder

2.7

5

14

7

51

1180

0

ULGZDMOVFRHVEP-ZFHWVPMOSA-N

InChI=1S/C37H67NO13/c1-14-25-37(10,45)30(41)20(4)27(39)18(2)16-35(8,44)32(51-34-28(40)24(38(11)12)15-19(3)47-34)21(5)29(22(6)33(43)49-25)50-26-17-36(9,46-13)31(42)23(7)48-26/h18-26,28-32,34,40-42,44-45H,14-17H2,1-13H3/t18-,19?,20+,21+,22-,23?,24?,25-,26?,28?,29+,30-,31?,32-,34?,35-,36?,37-/m1/s1/i11+1D3

(3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-14-ethyl-7,12,13-trihydroxy-4-(5-hydroxy-4-methoxy-4,6-dimethyloxan-2-yl)oxy-6-[3-hydroxy-6-methyl-4-[methyl(trideuterio(113C)methyl)amino]oxan-2-yl]oxy-3,5,7,9,11,13-hexamethyl-oxacyclotetradecane-2,10-dione

Erythromycin-d3

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)