Loratadine undergoes extensive first pass metabolism in the liver and is primarily metabolized by CYP3A4, CYP2D6, CYP1A1 and CYP2C19. Less involved CYP enzymes include CYP1A2, CYP2B6, CYP2C8, CYP2C9 and CYP3A5. CYP3A4 and CYP2D6 are mainly responsible for metabolizing loratadine to descarboethoxyloratadine. This primary metabolite is 4 times more pharmacologically active than loratadine. In addition, a study demonstrates that descarboethoxyloratadine is first glucuronidated by UGT2B10, then hydroxylated by CYP2C8 to form 3-hydroxydesloratadine. Further glucuronidation of 3-hydroxydesloratadine facilitates excretion.
The second generation H1 antagonists astemizole, loratadine,and terfenadine are rapidly absorbed from the gastrointestinal tract and metabolized in the liver to active metabolites by the hepatic microsomal p450 system.
Pharmacokinetic studies following single and multiple oral doses of loratadine in 115 volunteers showed that loratadine is rapidly absorbed and extensively metabolized to an active metabolite (descarboethoxyloratadine).
In vitro studies with human liver microsomes indicate that loratadine is metabolized to descarboethoxyloratadine predominately by p450 CYP3A4 and, to a lesser extent, by p450 CYP2D6.
来源:Hazardous Substances Data Bank (HSDB)
代谢
H1受体拮抗剂是诱导肝微粒体酶的许多药物之一，它们可能促进自身的代谢。/H1受体拮抗剂/
H1 receptor antagonists are among the many drugs that induce hepatic microsomal enzymes, and they may facilitate their own metabolism. /H1 Receptor Antagonists/
Loratadine competes with free histamine and exhibits specific, selective peripheral H<sub>1</sub> antagonistic activity. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms (eg. nasal congestion, watery eyes) brought on by histamine. Loratadine has low affinity for cholinergic receptors and does not exhibit any appreciable alpha-adrenergic blocking activity in-vitro. Loratadine also appears to suppress the release of histamine and leukotrienes from animal mast cells, and the release of leukotrienes from human lung fragments, although the clinical importance of this is unknown.
参考文献：M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. 用于研究药物诱导肝损伤的FDA批准药物标签，药物发现今日，16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank：按在人类中发展药物诱导肝损伤风险排名的最大参考药物清单。药物发现今日2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
References:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. FDA-Approved Drug Labeling for the Study of Drug-Induced Liver Injury, Drug Discovery Today, 16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank: the largest reference drug list ranked by the risk for developing drug-induced liver injury in humans. Drug Discov Today 2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
Loratadine is rapidly absorbed and achieves peak plasma concentration in 1-2 hours, while it's main metabolite achieves peak plasma concentration in 3-4 hours. In the rapid dissolve formulation, the pharmacokinetic parameters of loratadine are as follows: Cmax = 2.56 ng/ml, Tmax = 1.14 hrs, AUC = 6.14 ng x hr/ml. In the rapid dissolve formulation, the pharmacokinetic parameters of descarboethoxyloratadine are as follows: Cmax = 3.72 ng/ml, Tmax = 1.97 hr, AUC = 49.1 ng x hr/ml. In the conventional formulation, the pharmacokinetic parameters of loratadine are as follows: Cmax = 2.11 ng/ml, Tmax = 1.00 hr, AUC = 4.64 ng x hr/ml In the conventional formulation, the pharmacokinetic parameters of descarboethoxyloratadine are as follows: Cmax = 3.66 ng/ml, Tmax = 1.97 hr, AUC = 48.4 ng x hr/ml
来源:DrugBank
吸收、分配和排泄
消除途径
在10天的时间里，40%的洛拉他丁通过尿液排出，42%通过粪便排出。
Over a 10 day period, 40% of loratadine is excreted in the urine, and 42% is eliminated in the faeces.
来源:DrugBank
吸收、分配和排泄
分布容积
洛拉他丁的分布体积为120 L/Kg。
The volume of distribution of loratadine is 120 L/Kg.
The clearance of loratadine after single oral doses of 20 mg and 40 mg are 12 L/h/kg and 9 L/h/kg respectively. P-glycoprotein is involved in the clearance of many 2nd generation antihistamines, including loratadine, from the central nervous system. 1st generation antihistamines are not cleared by P-glycoprotein, which may help explain why they have a different central nervous system adverse effect profile compared to their 2nd generation counterparts. It appears that an antihistamine with higher affinity for p-glycoprotein will have a lower incidence of CNS adverse effects.
Compositions for Treatment of Cystic Fibrosis and Other Chronic Diseases
申请人：Vertex Pharmaceuticals Incorporated
公开号：US20150231142A1
公开（公告）日：2015-08-20
The present invention relates to pharmaceutical compositions comprising an inhibitor of epithelial sodium channel activity in combination with at least one ABC Transporter modulator compound of Formula A, Formula B, Formula C, or Formula D. The invention also relates to pharmaceutical formulations thereof, and to methods of using such compositions in the treatment of CFTR mediated diseases, particularly cystic fibrosis using the pharmaceutical combination compositions.
The present invention relates compounds of the formula: or pharmaceutically acceptable salts thereof, useful as sodium channel blockers, as well as compositions containing the same, processes for the preparation of the same, and therapeutic methods of use therefore in promoting hydration of mucosal surfaces and the treatment of diseases including cystic fibrosis, chronic obstructive pulmonary disease, asthma, bronchiectasis, acute and chronic bronchitis, emphysema, and pneumonia.
CHLORO-PYRAZINE CARBOXAMIDE DERIVATIVES WITH EPITHELIAL SODIUM CHANNEL BLOCKING ACTIVITY
申请人：Parion Sciences, Inc.
公开号：US20140171447A1
公开（公告）日：2014-06-19
This invention provides compounds of the formula I:
and their pharmaceutically acceptable salts, useful as sodium channel blockers, compositions containing the same, therapeutic methods and uses for the same and processes for preparing the same.
The present invention is directed to novel compounds of Formula (I) and pharmaceutically acceptable salts thereof,
pharmaceutical compositions and their use as dual chromaphores having inhibitory activity against PDE4 and muscarinic acetylcholine receptors (mAChRs), and thus being useful for treating respiratory diseases.
[EN] DUAL PHARMACOPHORES - PDE4-MUSCARINIC ANTAGONISTICS<br/>[FR] PHARMACOPHORES DUALS, ANTAGONISTES DES RÉCEPTEURS MUSCARINIQUES ET INHIBITEURS DE L'ACTIVITÉ PDE4
申请人：GLAXO GROUP LTD
公开号：WO2009100169A1
公开（公告）日：2009-08-13
The present invention is directed to novel compounds of Formula's (I) - (VI), and pharmaceutically acceptable salts thereof, pharmaceutical compositions and their use in therapy, for example as inhibitors of phosphodiesterase type IV (PDE4) and as antagonists of muscarinic acetylcholine receptors (mAChRs), in the treatment of and/or prophylaxis of respiratory diseases, including inflammatory and/or allergic diseases such as chronic obstructive pulmonary disease (COPD), asthma, rhinitis (e.g. allergic rhinitis), atopic dermatitis or psoriasis.
