Demeclocycline : Therapeutic uses, Dosage & Side Effects
Demeclocycline is an broad spectrum tetracycline antibiotic. It is used for treating infections caused by susceptible bacteria.
Dose : 150-300 mg BD
Route : Oral
Onset of action : ?
Plasma Half-life : 16-18 hours
Duration of action : ?
Bioavailability : 60–80%
Plasma protein binding : 41–50% (High)
Metabolism : Hepatic
Pregnancy risk category : D
Chemical formula : C21H21ClN2O8
IUPAC name : (2E,4S,4aS,5aS,6S,12aS)-2-[amino(hydroxy)methylidene]-7-chloro-4-(dimethylamino)-6,10,11,12a-tetrahydroxy-1,2,3,4,4a,5,5a,6,12,12a-decahydrotetracene-1,3,12-trione
Trade name : Ledermycin, Declomycin, DDeclostatin, Bioterciclin, Deganol, Deteclo, Detravis, Meciclin, Mexocine, Clortetrin
Antibacterial spectrum : Demeclocycline has been shown to be active against most isolates of the following microbes :
- Gram-positive bacteria : Bacillus anthracis, Listeria monocytogenes, Staphy. aureus, Strep. pneumoniae
- Gram-negative bacteria : Calymmatobacterium granulomatis, Bartonella bacilliformis, Brucella species, Campylobacter fetus, Francisella tularensis, H. ducreyi, H. influenzae, N. gonorrhoeae, Vibrio cholerae, Yersinia pestis
- Actinomyces israelii, Borrelia recurrentis, Chlamydia psittaci, Chlamydia trachomatis, Clostridium species, Fusobacterium fusiforme, Propionibacterium acnes, Rickettsiae, Treponema pallidum, Entamoeba species, Mycoplasma pneumoniae, Ureaplasma urealyticum
Therapeutic uses : Demeclocycline is indicated for treatment of following infections caused by susceptible strains of the microorganisms :
- Respiratory tract infections
- Lymphogranuloma venereum
- Psittacosis (Ornithosis)
- Trachoma, Inclusion conjunctivitis
- Nongonococcal urethritis
- Relapsing fever, Chancroid, Plague
- Campylobacter fetus infections
- Granuloma inguinale
In acute intestinal amebiasis, it may be a useful adjunct to amebicides while in severe acne, it may be a useful adjunctive therapy.
Syphilis, Yaws, Listeriosis, Vincent’s infection, Anthrax, Actinomycosis, Clostridial diseases etc. should be treated with Demeclocycline only when bacteriologic testing indicates appropriate susceptibility to the drug.
Mechanism of action : Tetracyclines enter susceptible organisms via passive diffusion & by an energy-dependent transport protein mechanism unique to the bacterial inner cytoplasmic membrane. Tetracyclines concentrate intracellularly in susceptible organisms. The drugs bind reversibly to the 30S subunit of the bacterial ribosome. This action prevents binding of aminoacyl-t-RNA to the mRNA–ribosome complex, thereby inhibiting bacterial protein synthesis.
Side effects : Demeclocycline may cause following side effects :
- Irritative effects : Epigastric pain, nausea, vomiting, diarrhoea. The irritative diarrhoea is to be distinguished from that due to superinfection.
- Thrombophlebitis of the injected vein.
- Kidney damage (prominent only in the presence of existing kidney disease).
- A reversible Fancony syndrome like condition is produced by outdated tetracyclines due to proximal tubular damage caused by degraded products-epitetracycline, anhydrotetracycline and epianhydrotetracycline. Exposure to acidic pH, moisture and heat favours such degradation.
- Phototoxicity (Distortion of nails occurs occasionally)
- Liver damage : Fatty infiltration of liver and jaundice occurs occasionally.
- Antianabolic effect : Reduce protein synthesis and cause an overall catabolic effect. It induces negative nitrogen balance and can increase blood urea.
- Increased intracranial pressure is noted insome infants.
- Hypersensitivity reactions (infrequent) : Skin rashes, urticaria, glossitis, pruritus ani and vulvae, even exfoliative dermatitis have been reported. Complete cross sensitization is exhibited by different tetracyclines.
- Diabetes insipidus : Demeclocycline antagonizes ADH action and reduces urine concentrating ability of the kidney. It has been tried in patients with inappropriate ADH secretion.
- Superinfection : Tetracyclines are the most common antibiotics responsible for superinfections, because they cause marked suppression of the resident flora.
- Teeth and bones : Tetracyclines have chelating property. Calcium-tetracycline chelate gets deposited in developing teeth and bone. Given from midpregnancy to 5 months of extrauterine life, the deciduous teeth are affected: brown discolouration, ill-formed teeth, more susceptible to caries. Tetracyclines given between 3 months and 6 years of age affect the crown of permanent anterior dentition. Repeated courses are more damaging.
Given during late pregnancy or childhood, tetracyclines can cause temporary suppression of bone growth. The ultimate effect on stature is mostly insignificant, but deformities and reduction in height are a possibility with prolonged use.
Drug Interactions : Demeclocycline may interact with following drugs :
- Methoxyflurane : fatal renal toxicity
- Antacids containing Al, Ca or Mg and preparations containing Fe : Absorption of tetracyclines impaired
- Oral contraceptives : Decreased effectiveness of contraceptives
- Contraindicated in persons who have shown hypersensitivity to any of the tetracyclines.
- Should not be used in pregnant or breast-feeding women or in children less than 8 years of age.
For detailed query or in case of uncertainty, Always consult your doctor or pharmacist.