A tetracycline analog having a 7-chloro and a 6-methyl. Because it is excreted more slowly than tetracycline, it maintains effective blood levels for longer periods of time. [PubChem]
Indication
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.
Toxicity
Oral, rat: LD50 = 2372 mg/kg
Affected Organisms
Enteric bacteria and other eubacteria
Biotransformation
Hepatic
Absorption
Tetracyclines are readily absorbed.
Half Life
10-17 hours
Protein Binding
41-50%
Elimination
Demeclocycline hydrochloride, like other tetracyclines, is concentrated in the liver and excreted into the bile where it is found in much higher concentrations than in the blood. Following a single 150 mg dose of demeclocycline hydrochloride in normal volunteers, 44% (n = 8) was excreted in urine and 13% and 46%, respectively, were excreted in feces in two patients within 96 hours as active drug.
Clearance
* Renal cl=35 mL/min/1.73 m2
References
•
De Troyer A, Demanet JC: Correction of antidiuresis by demeclocycline. N Engl J Med. 1975 Oct 30;293(18):915-8.
[Pubmed]
