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In clinical work, we all know that some diseases can cause skin itching, such as uremia, biliary cirrhosis, hyperthyroidism or hypothyroidism, diabetes, and malignancy. However, some skin itching is caused by medication. As a doctor, we must be alert to the itching of medicinal skin and avoid too many detours during the treatment.

I. Quinolones

First generation, nalidixic acid and pyrrolic acid; second generation, cinoxacin and pipemidic acid; third generation, norfloxacin, enoxacin, ciprofloxacin, ofloxacin, lomesa Star, pefloxacin, fleroxacin, tocoxacin, and sparfloxacin; fourth generation, moxifloxacin, clinfloxacin, gemifloxacin.

Studies have found that quinolones can cause skin phototoxicity and lead to pruritus. The specific mechanisms are as follows: (1) The free radicals produced by the oxidation of quinolones can change the structure of guanine, resulting in DNA damage in vivo and cytotoxicity. . 2 Quinolones oxidize to form reactive oxygen species, activate protein kinase C and tyrosine kinases of skin fibroblasts, promote the synthesis and release of cyclooxygenase products, and cause inflammation of the skin. Active oxygen includes superoxide anion radicals and peroxidation. Hydrogen, hydroxyl radicals, and singlet oxygen can cause peroxidation of unsaturated fatty acids in biofilms, resulting in lipid peroxides, disruption of cell membranes, damage to local tissues, inflammation of the skin that causes infiltration of leukocytes, and production of pigments. calm.

II. Metronidazole

It is mainly used to treat or prevent systemic or local infections caused by anaerobic bacteria such as anaerobic infections in the abdominal cavity, digestive tract, female reproductive system, lower respiratory tract, skin and soft tissues, bones and joints, etc. Messitis, meningeal infection, and colitis caused by the use of antibiotics are also effective. The study found that metronidazole can cause skin pruritus and rash, domestic metronidazole caused fixed drug eruption, rose herpes-like rash and erythema multiforme drug eruption reported.

III. Proton Pump Inhibitors

Proton pump inhibitors can selectively act on gastric mucosal wall cells, inhibiting the activity of H+-K+-ATPase on secretory microtubules and tubular vacuoles in the apical membrane of the parietal cells, thereby effectively suppressing gastric acid Secretion. Applicable to gastric and duodenal ulcers, reflux or erosive esophagitis, Zoe – Er’s syndrome. The commonly used proton pump inhibitors are omeprazole, pantoprazole, lansoprazole, rabeprazole, and esomeprazole. Studies have found that taking proton pump inhibitors can cause erythema, systemic skin itching, urticaria, herpes, etc., can also appear life-threatening toxic epidermal necrolysis and anaphylactic shock.

IV. Opioid drugs

It is an alkaloid extracted from opium (Papaver somniferum) and derivatives in vitro and in vivo. It interacts with central receptor-specific receptors and relieves pain. Opium alkaloids and their semi-synthetic derivatives include morphine, diethylmorphine (heroin), Hydromorphine, codeine, oxycodone. Synthetic morphine substances include levamin, propoxyphene, fentanyl, methadone, pethidine and agonist-antagonist pentazocine. Opioids can cause pruritus. The study found that the presence of a central pruritus, including the trigeminal nucleus, in the lower medulla oblongata of the body plays an important role in the development of pruritus. Opioids may affect the central nervous system and may trigger itching centers.

V. Calcium antagonists

Calcium antagonists can selectively inhibit Ca2+ from entering the cell via calcium channels on the cell membrane, and have the effect of dilating blood vessels and negative inotropic forces, relaxing vascular smooth muscle, reducing peripheral vascular resistance, and thus lowering blood pressure. There are three commonly used calcium antagonists in clinical practice: phenalamines (such as verapamil); dihydropyridines (such as a generation of nifedipine; second-generation sustained-release nifedipine, felodipine; three generations of lacidipine Amlodipine; four generations of cilnidipine); diltiazem (such as diltiazem). Studies have found that calcium antagonists can cause rashes and allergic reactions.

VI. Low Molecular Dextran

Low-molecular-weight dextran contains a small amount of macromolecular dextran. The larger the molecular weight, the slower excretion and accumulation in the body. This may be the cause of pruritus.

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