Chlortetracycline

Absorption

Chortetracycline reaches peak plasma concentation in about 3 hours . Its oral bioavailability is 25-30%.

Toxicity

The acute oral LD50 in mice is 2314mg/kg .The most common adverse effects of tertacylines are gastrointestinal disturbances, and staining of teeth and bone. Some occurences of dental hypoplasia and bone deformity have been noted . In pregnant women tetracyclines may produce hepatotoxicity.

Originator

Aureomycin, Lederle, US ,1948

The Uses of Chlortetracycline

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.

Background

Chlortetracycline is a tetracycline antibiotic, and historically the first member of this class to be identified. It was discovered in 1945 by the scientist, Benjamin Minge Duggar, working at Lederle Laboratories under the supervision of Yellapragada Subbarow. He discovered that this antibiotic was the product of an actinomycete strain he cultured and obtained from a soil sample from a field in Missouri. The organism was named Streptomyces aureofaciens due to its gold-hued color.

Indications

Used in the manufacuring of medicated animal feeds .

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

Tetracycline antibiotics are bacteriostatic agents which act to inhibit bacterial growth and reproduction .

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.

Metabolism

Chlortetracycline is not known to undergo significant metabolism .

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.]