Absorption, Distribution and Excretion
H1 receptor antagonists are readily absorbed from the gastrointestinal tract. Peak plasma concentrations are reached within 2 to 3 hours after oral administration, and the effect typically lasts 4 to 6 hours; however, some drugs have a longer duration of action… /Histamine Antagonists: H1 Receptor Antagonists/ Children clear H1 receptor antagonists faster than adults, while clearance is slower in patients with severe liver disease. /Histamine Antagonists: H1 Receptor Antagonists/

---

Metabolism/Metabolites The primary site of metabolic transformation is the liver. /Antichrists/ H1 receptor blockers are among many drugs that induce hepatic microsomal enzymes, which may promote their own metabolism. /Histamine Antagonists: H1 Receptor Antagonists/

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Occasional use of low doses of piracetam during lactation may be acceptable. Higher doses or prolonged use may affect the infant or reduce milk production, especially when used in combination with sympathomimetic drugs (such as pseudoephedrine) or before lactation is fully established. Non-sedating antihistamines are a better alternative.
◉ Effects on Breastfed Infants
As of the revision date, no published information was found regarding piracetam. In a telephone follow-up study, mothers reported that 10% of their infants experienced irritability and colic after taking various antihistamines, and 1.6% experienced lethargy. All adverse reactions were non-medical, and all infants were not exposed to piracetam.
◉ Effects on Lactation and Breast Milk
Higher doses of injected antihistamines can lower baseline serum prolactin levels in non-lactating women and early postpartum women. However, pre-administration of antihistamines by postpartum mothers does not affect suckling-induced prolactin secretion. Whether lower oral doses of antihistamines have the same effect on serum prolactin, and whether their effect on prolactin has any impact on breastfeeding success, is currently unstudied. Prolactin levels in established lactating mothers may not affect their breastfeeding ability.

---

Interactions
Concomitant use of ototoxic drugs and antihistamines may mask ototoxic symptoms such as tinnitus, dizziness, or vertigo. /Antihistamines/
Concomitant use of monoamine oxidase (MAO) inhibitors with antihistamines may prolong and enhance the anticholinergic and central nervous system depressant effects of antihistamines; concomitant use is not recommended. /Antihistamines/
Concomitant use with alcohol or other central nervous system depressants may enhance the central nervous system depressant effects of these drugs or antihistamines; furthermore, concomitant use with maprotiline or tricyclic antidepressants may enhance the antihistamine or anticholinergic effects of these drugs. /Antihistamines/
When anticholinergic drugs or other drugs with anticholinergic activity are used in combination with antihistamines, the anticholinergic effect may be enhanced; patients should be advised to report gastrointestinal problems promptly, as combined use may lead to paralytic ileus. Antihistamines
Concurrent use of other photosensitizing drugs and antihistamines may produce additive photosensitizing effects.

Pyrilamine is a viscous, brown liquid. (NTP, 1992)
Pyrilamine is an ethylenediamine derivative with the structure of an ethylenediamine molecule, in which one amino nitrogen atom is replaced by two methyl groups, and the other amino nitrogen atom is replaced by a 4-methoxybenzyl and a pyridin-2-yl group. It is an H1 receptor antagonist. It is an ethylenediamine derivative and also an aromatic ether.
Pyrilamine (or pyramine) targets the H1 receptor. It is a first-generation antihistamine. However, it can rapidly penetrate the brain, thus often causing side effects such as drowsiness. It was once added to over-the-counter combination preparations for treating cold and menstrual symptoms, but is currently considered an unapproved prescription drug for treating coughs, colds, or allergies.
Histamine H1 receptor antagonist. It has mild hypnotic effects and some local anesthetic effects, and can be used to treat allergies (including rashes), both parenterally and topically. It is a common ingredient in cold medicines.
See also: Pyrilamine maleate (in salt form). Drug Indications This drug is indicated for the treatment of allergic diseases, relief of allergic reaction symptoms, and treatment of pruritic skin conditions. Mechanism of Action Mepiracetam is a histamine H1 receptor inverse agonist. It binds to the G protein-coupled form of the receptor, promoting the H1 receptor to enter a G protein-coupled inactive state, thereby interfering with Gq/11-mediated signaling. Mepiracetam competes with histamine for H1 receptor sites on the surface of effector cells, thereby inhibiting histamine-induced subcutaneous edema, erythema, and pruritus. The sedative effect of mepiracetam occurs at the subcortical level of the central nervous system. Antihistamines used to treat allergies act by competing with histamine for H1 receptor sites on effector cells. They can prevent (but cannot reverse) reactions mediated solely by histamine. Antihistamines antagonize most of the pharmacological effects of histamine to varying degrees, including urticaria and pruritus. In addition, the anticholinergic effects of most antihistamines can cause nasal dryness. H1 receptor antagonists inhibit most smooth muscle responses to histamine. The antagonistic effect of histamine on the contraction of respiratory smooth muscle is readily demonstrated both in vivo and in vitro. /Histamine antagonists: H1 receptor antagonists/
H1 receptor antagonists potently block the effects of histamine, thereby reducing increased vascular permeability and the formation of edema and wheals. /Histamine antagonists: H1 receptor antagonists/
Some H1 receptor antagonists have local anesthetic activity… /Histamine antagonists: H1 receptor antagonists/
For more complete data on the mechanisms of action of piracetam (6 in total), please visit the HSDB record page.

---

Therapeutic Uses
Antihistamines; Histamine H1 Receptor Antagonists
Antihistamines are indicated for the prevention and treatment of perennial and seasonal allergic rhinitis, vasomotor rhinitis, and allergic conjunctivitis caused by inhaled allergens and foods. /Antihistamines; already included on the US product label/
Antihistamines are indicated for the treatment of itching associated with allergic reactions, and mild, uncomplicated allergic skin manifestations such as urticaria and angioedema, dermatographia, and transfusion-associated urticaria. /Antihistamines; already included on the US product label/
Antihistamines are also used to treat itching associated with pityriasis rosea. /Antihistamines; this information is not included on the US product label/
For more complete data on the therapeutic uses of piracetam (11 in total), please visit the HSDB record page.

---

Drug Warnings
Use is not recommended for newborns or premature infants because this age group is more sensitive to anticholinergic side effects (such as central nervous system excitation) and is more prone to seizures. Children taking antihistamines may experience paradoxical reactions characterized by hyperexcitability. /Antihistamines/
Elderly patients are more likely to experience dizziness, sedation, confusion, and hypotension after taking antihistamines. Elderly patients are particularly susceptible to the anticholinergic side effects of antihistamines, such as dry mouth and urinary retention (especially in men). If these side effects occur and persist or are severe, discontinuation of the medication should be considered. /Anthistamines/
Prolonged use of antihistamines…may reduce or suppress saliva production, leading to tooth decay, periodontitis, oral candidiasis, and discomfort. /Anthistamines/
H1 receptor antagonists are best suited for acute exudative allergies presenting with symptoms of rhinitis, urticaria, and conjunctivitis. However, their effect is limited to symptom relief, limited to suppressing the symptoms caused by the histamine-antibody reaction. These medications do not reduce the intensity of this reaction, which is the cause of various allergic diseases. /Histamine Antagonists: H1 Receptor Antagonists/
For more complete data on drug warnings for piracetam (11 in total), please visit the HSDB record page.

C17H23N3O

285.39

285.184

91-84-9

59-33-6;91-84-9;6036-95-9 (HCl);

4992

OILY LIQUID

1.0141 (rough estimate)

201ºC at 5 MM HG

MELTING POINT: 143-143.5 °C /HYDROCHLORIDE/, 100-101 °C /MALEATE/

nD25 1.5760-1.5765

2.658

0

4

7

21

277

0

CN(C)CCN(CC1=CC=C(C=C1)OC)C2=CC=CC=N2

YECBIJXISLIIDS-UHFFFAOYSA-N

InChI=1S/C17H23N3O/c1-19(2)12-13-20(17-6-4-5-11-18-17)14-15-7-9-16(21-3)10-8-15/h4-11H,12-14H2,1-3H3

N'-[(4-methoxyphenyl)methyl]-N,N-dimethyl-N'-pyridin-2-ylethane-1,2-diamine

NSC-13136; NSC 13136; Mepyramine

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.

---

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).

View More

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)

---

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).

View More

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

---

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.

---

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