Description
Chlortetracycline (Brand name: Aureomycin) is the 7-chloro substitution derivative of the tetracycline and has a golden color. As a veterinary medicine, chlortetracycline is commonly used for the treatment of conjunctivitis of cats. It can also be used in the treatment of infections occurring in the urinary tract, respiratory tract, and the intestines. Its mechanism of action is through inhibiting the protein synthesis, inhibiting the binding of aminoacyl-tRNA to the mRNA-ribosome complex through binding to the 30S ribosome subunit.
Originator
Aureomycin, Lederle, US ,1948
Uses
Chlortetracycline was the first reported member of the tetracycline class, isolated from Streptomyces aureofaciens in 1948. Chlortetracyclines heralded the early wave of antibiotic discoveries from microbes and after 50 years are still widely used as pharmaceuticals. Chlortetracycline is a pigment and, like most pigments, is extremely sensitive to environmental and storage conditions. Commercial chlortetracycline may contain significant levels of degradation products.
Definition
ChEBI: A member of the class of tetracyclines with formula C22H23ClN2O8 isolated from Streptomyces aureofaciens.
Indications
Chlorotetracycline, an antibiotic with a broad spectrum of action, causes a bacteriostatic
effect with respect to Gram-positive (staphylococci, including those that produce penicillinase; streptococci, pneumococci; clostridia, listeria, and anthrax bacillus) and Gram-negative
microorganisms (gonococci, whooping cough bacillus, colon bacillus, enterobacteria,
klebisella, salmonella, shigella), as well as Rickettsia, chlamydia, mycoplasma, and
spirochaeta. Blue-pus bacillus, proteus, serracia, most strains of Bacteroides fragilis, most
fungi, and small viruses are resistant to this drug. It is used for pneumonia, bronchitis,
empyema of the lungs, angina, cholecystitis, whooping cough, endocarditis, endometritis,
intestinal infections, prostatitis, syphilis, gonorrhea, brucellosis, osteomyelitis, purulent
infections of soft tissues, and others caused by microorganisms sensitive to this drug.
Synonyms of this drug are aureomycin, biomycin, xanthomycin, and others.
Manufacturing Process
The following process description is taken from US Patent 2,987,449. An
appropriate S. aureofaciens strain such as mutant S1308 (ATCC No. 12,748) is
grown aerobically in a suitable inoculum medium. A typical medium used to
grow the primary inoculum is prepared according to the following formula:
sucrose, 20.0 g; corn steep liquor, 16.5 ml, ammonium sulfate, 2.0 g; calcium
carbonate, 7.0 g; and water to 1,000 ml.
A 100 ml aliquot of this medium is placed in a 500 mi Erlenmeyer flask and
sterilized by autoclaving for 20 minutes under 15 psi pressure. Spores of
mutant strain S. aureofaciens S1308 (ATCC No. 12,748) are washed from an
agar slant into the flask with sterile distilled water to form a suspension
containing approximately 108 spores per milliliter. A 1.0 ml portion of this
suspension is used to inoculate the fermentation media in the example which
follows. A fermentation medium consisting of the following ingredients was
prepared.
25 ml aliquots of this fermentation medium were placed in each of two 250 ml
Erlenmeyer flasks and 0.5 ml of lard oil was added to each flask. Then 0.002
mg/ml of riboflavin was added to one flask, the other flask being retained as a
control. The flasks were sterilized in an autoclave for 20 minutes under 15 psi
pressure, then cooled to room temperature (25°±5°C). At this point, a 1.0 ml
portion of inoculum of mutant strain S. aureofaciens S1308 (ATCC No.
12,748) was added to each of the two flasks. The flasks were incubated at25°C for 120 hours on a rotary shaker operating at 180 rpm. Upon completion
of the fermentation period the mashes were assayed for 7-chlorotetracycline
content.
The increase in production due to the addition of riboflavin was very
noticeable in the above example. A similar effect was reported for cupric
sulfate pentahydrate addition according to US Patent 3,050,446.
Therapeutic Function
Antibacterial
Antimicrobial activity
It is slightly less active than tetracycline against many
bacteria, with the exception of Gram-positive organisms.
Pharmaceutical Applications
7-Chlortetracycline. A fermentation product of certain strains
of Streptomyces aureofaciens. Formulated as the hydrochloride
or the free base for oral or topical application.
Pharmacokinetics
Oral absorption：30–60%
C
max 500 mg oral：2.5–7 mg/L：
Plasma half-life： 5–6 h
Volume of distribution： c.2 L/kg
Plasma protein binding： 47–65%
Absorption is relatively poor compared with other tetracyclines.
It undergoes rapid metabolism and is largely eliminated by biliary
excretion, with only a small proportion eliminated via the
kidney. Despite this, chlortetracycline is not recommended for
patients in renal failure, since accumulation occurs as a consequence
of the half-life increase to approximately 7–11 h.
Clinical Use
Its uses are those common to the group.
It has also been used topically in the management of recurrent
aphthous ulcers of the mouth, but experience is limited
and the mechanism of action is unknown.
Side effects
Side effects are typical of the group. Contact hypersensitivity
has been reported with topical application to
abraded skin and varicose ulcers.
Safety Profile
Poison by intravenous
and intraperitoneal routes. Moderately toxic
by ingestion. Experimental reproductive
effects. When heated to decomposition it
emits toxic fumes of Cland NOx. See also
TETRACYCLINE.
Synthesis
Chlorotetracyline, 7-chloro-4-dimethylamino-1,4,4a,5,5a,6,11,12aoxtahydro-3,6,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-2-naphthacencarboxamide
(32.3.1), is obtained biosynthetically as a result of the activity of a microorganism, the actinomycete S. aureofaciens.
Veterinary Drugs and Treatments
There are a variety of approved chlortetracycline products for use in
food animals.
It may also be useful in treating susceptible infections
in dogs, cats, birds and small mammals (not Guinea pigs). For more
information, refer to the Doses section below.
Purification Methods
Aureomycin is dehydrated by azeotropic distillation of its solution with toluene. On cooling, the anhydrous material crystallises out and is recrystallised from *C6H6, then dried under vacuum at 100o over paraffin wax. (If it is crystallised from MeOH, it contains MeOH which is not removed on drying.) [Stephens et al. J Am Chem Soc 76 3568 1954, Laskin & Chan Biochem Biophys Res Commun 14 137 1964]. [Beilstein 14 IV 2631.]
