Brands, Medical Use, Clinical Data
Drug Category
- Anti-bacterial Agents
- Tetracyclines
Dosage Forms
Brands / Synonyms
6-Demethyl-7-chlorotetracycline; 6-Demethylchlorotetracycline; 7-Chloro-6-demethyltetracycline; Bioterciclin; Clortetrin; Declomycin; Deganol; Demeclociclina [INN-Spanish]; Demeclocycline; Demeclocycline HCL; Demeclocycline hydrochloride; Demeclocycline [USAN:BAN]; Demeclocyclinum [INN-Latin]; Demeclor; Demethylchlorotetracycline; Demethylchlortetracyclin; Demethylchlortetracycline; Demethylchlortetracycline hydrochloride; Demethylchlortetracyclinum; Demetraclin; Diuciclin; DMCT; DMCT (antibiotic); Elkamicina; Ledermycin; Ledermycin hydrochloride; Methylchlorotetracycline; Mexocine; Novotriclina; Perciclina; Sumaclina; Tri-demethylchlortetracycline
Indications
Used primarily to treat Lyme disease, acne, and bronchitis. Also indicated (but rarely used) to treat urinary tract infections, gum disease, malaria, and other bacterial infections such as gonorrhea and chlamydia. One of its other registered uses is the treatment of hyponatremia (low blood sodium concentration) due to the syndrome of inappropriate antidiuretic hormone (SIADH) where fluid restriction alone has been ineffective.
Pharmacology
Demeclocycline is a tetracycline antibiotic active against the following microorganisms: Rickettsiae (Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsial pox, tick fevers), Mycoplasma pneumoniae (PPLO, Eaton agent), agents of psittacosis and ornithosis, agents of lymphogranulomavenereum and granuloma inguinale, the spirochetal agent of relapsing fever (Borrelia recurrentis), Haemophilus ducreyi (chancroid), Yersinia pestis, Pasteurella pestis and Pasteurella tularensis, Bartonella bacilliformis, Bacteroides species, Vibrio comma and Vibrio fetus, and Brucella species (in conjunction with streptomycin). Demeclocycline inhibits cell growth by inhibiting translation. Demeclocycline is lipophilic and can easily pass through the cell membrane or passively diffuses through porin channels in the bacterial membrane. Demeclocycline is bacteriostatic (it impairs bacterial growth but does not kill bacteria directly). Because it is excreted more slowly than tetracycline, it maintains effective blood levels for longer periods of time.
Mechanism of Action
Demeclocycline inhibits cell growth by inhibiting translation. It binds (reversibly) to the 30S and 50S ribosomal subunit and prevents the amino-acyl tRNA from binding to the A site of the ribosome, which impairs protein synthesis by bacteria. The binding is reversible in nature. The use in SIADH actually relies on a side-effect of tetracycline antibiotics; many may cause diabetes insipidus (dehydration due to the inability to concentrate urine). It is not completely understood why demeclocycline impairs the action of antidiuretic hormone, but it is thought that it blocks the binding of the hormone to its receptor.
Absorption
Tetracyclines are readily absorbed.
Toxicity
Oral, rat: LD50 = 2372 mg/kg
Biotrnasformation / Drug Metabolism
Hepatic
Contraindications
This drug is contraindicated in persons who have shown hypersensitivity to any of the tetracyclines.
Drug Interactions
Because the tetracyclines have been shown to depress plasma prothrombin activity, patients who are on
anticoagulant therapy may require downward adjustment of their anticoagulant dosage.
Since bacteriostatic drugs, such as the tetracycline class of antibiotics, may interfere with the bactericidal
action of penicillins, it is not advisable to administer these drugs concomitantly.
Concurrent use of tetracyclines with oral contraceptives may render oral contraceptives less effective.
Breakthrough bleeding has been reported
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