Chemistry - An antibiotic obtained from Streptomyces aureofaciens, or derived semisynthetically from oxytetracycline, tetracycline HCl occurs as a moderately hygroscopic, yellow, crystalline powder. About 100 mg/ml is soluble in water and 10 mg/ml soluble in alcohol. Tetracycline base has a solubility of about 0.4 mg per ml of water and 20 mg per ml of alcohol. Commercially available tetracycline HCl for IM injection also contains magnesium chloride, procaine HCl and ascorbic acid.
Storage/Stability/Compatibility - Unless otherwise instructed by the manufacturer, tetracycline oral tablets and capsules should be stored in tight, light resistant containers at room temperature (15-30°C). The oral suspension and powder for injection should be stored at room temperature. Avoid freezing the oral suspension.
After reconstituting the IM product, it may be stored at room temperature but should be used within 24 hours of reconstitution. After reconstituting the intravenous product with sterile water to a concentration of 50 mg/ml, the preparation is stable for 12 hours at room temperature. If further diluted in an appropriate IV fluid, use immediately.
Tetracycline HCl for intravenous injection is reportedly compatible with the following IV fluids and drugs: 0.9% sodium chloride, D5W, D5W in normal saline, Ringer’s injection, lactated Ringer’s injection, 10% invert sugar, dextrose-Ringer’s and lactated Ringer’s combinations, ascorbic acid, cimetidine HCl, colistimethate sodium, corticotropin, ephedrine sulfate, isoproterenol HCl, kanamycin sulfate, lidocaine HCl, metaraminol bitartrate, norepinephrine bitartrate, oxytetracycline HCl, oxytocin, potassium chloride, prednisolone sodium phosphate, procaine HCl, promazine HCl, and vitamin B complex with C.
Drugs that are reportedly incompatible with tetracycline, data conflicts, or compatibility is concentration/time dependent, include: amikacin sulfate, aminophylline, ampicillin sodium, amobarbital sodium, amphotericin B, calcium chloride/gluconate, carbenicillin disodium, cephalothin sodium, cephapirin sodium, chloramphenicol sodium succinate, dimenhydrinate, erythromycin gluceptate/lactobionate, heparin sodium, hydrocortisone sodium succinate, meperidine HCl, morphine sulfate, methicillin sodium, methohexital sodium, methyldopate HCl, oxacillin sodium, penicillin G potassium/sodium, phenobarbital sodium, sodium bicarbonate, thiopental sodium, and warfarin sodium. Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used. It is suggested to consult specialized references for more specific information (e.g., Handbook on Injectable Drugs by Trissel; see bibliography).
Pharmacology/Uses/Indications - Refer to the oxytetracycline monograph just preceding this one for information for tetracycline.
Pharmacokinetics - Both oxytetracycline and tetracycline are readily absorbed after oral administration to fasting animals. Bioavailabilities are approximately 60-80%. The presence of food or dairy products can significantly reduce the amount of tetracycline absorbed, with reductions of 50% or more possible. After IM administration, tetracycline is erratically and poorly absorbed with serum levels usually lower than those attainable with oral therapy.
Tetracyclines as a class, are widely distributed to heart, kidney, lungs, muscle, pleural fluid, bronchial secretions, sputum, bile, saliva, urine, synovial fluid, ascitic fluid, and aqueous and vitreous humor. Only small quantities of tetracycline and oxytetracycline are distributed to the CSF, and therapeutic levels may not be achievable. While all tetracyclines distribute to the prostate and eye, doxycycline or minocycline penetrate better into these and most other tissues. Tetracyclines cross the placenta, enter fetal circulation and are distributed into milk. The volume of distribution of tetracycline is approximately 1.2 - 1.3 L/kg in small animals. The amount of plasma protein binding is about 20 - 67% for tetracycline.
Both oxytetracycline and tetracycline are eliminated unchanged primarily via glomerular filtration. Patients with impaired renal function can have prolonged elimination half-lives and may accumulate the drug with repeated dosing. These drugs apparently are not metabolized, but are excreted into the GI tract via both biliary and nonbiliary routes and may become inactive after chelation with fecal materials. The elimination half-life of tetracycline is approximately 5-6 hours in dogs and cats.
Adverse Effects/Warnings/ Overdosage/Acute Toxicity/Drug Interactions/-Drug-Laboratory Interactions - Refer to the oxytetracycline monograph for information for tetracycline.
For susceptible infections:
a) 5 - 7.5 mg/kg IV q12h (Brumbaugh 1987)
Monitoring Parameters -
1) Adverse effects
2) Clinical efficacy
3) Long-term use or in susceptible patients: periodic renal, hepatic, hematologic evaluations
Client Information - Avoid giving this drug orally within 1-2 hours of feeding, giving milk or dairy products. If gastrointestinal upset occurs, giving with a small amount of food may help, but this will also reduce the amount drug absorbed.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Veterinary -Approved Products:
Tetracycline Oral Suspension 100 mg/ml (approximately 5 mg/drop) in 15 ml and 30 ml bottles
Panmycin Aquadrops® (Upjohn); (Rx) Approved for use in dogs and cats.
Tetracycline HCl Oral Boluses 500 mg
Polyotic® Oblets® (American Cyanimid) (Rx) Approved for use in calves and sheep. Slaughter withdrawal = 12 days calves; = 5 days sheep.
Panmycin® Oral Boluses (Upjohn); (OTC) Approved for use in calves. Slaughter withdrawal = 12 days.
Tetracycline HCl Soluble Powder as a water additive
Polyotic Soluble Powder® (10 g or 25 g tetracycline HCl/lb); (OTC)
Polyotic Soluble Powder Concentrate® (102.4 g tetracycline HCl/lb); (OTC) Both are approved for use in calves, and swine. Slaughter withdrawal = 4 days calves; = 7 days swine
Tetracycline HCl Soluble Powder-324® (324 g tetracycline HCl/lb); (OTC) Approved for use in calves, swine, chickens, and turkeys. Slaughter withdrawal = 4 days swine, chickens, and turkeys; = 5 days calves
Tetracycline HCl Oral Capsules: 100 mg (capsules only from Richlyn Labs), 250 mg, 500 mg; Many trade names, including: Achromycin-V® (Lederle), Sumycin '250'® & 500 (Apothecon); Panmycin® (Upjohn), generic; (Rx)
Tetracycline HCl Tablets: 500 mg; Tetracycline® (Dr's Pharm); Sumycin 500® (Apothecon) (Rx)
Tetracycline HCl Oral Suspension 25 mg/ml in 60, 473, & 480 ml; Achromycin-V® (Lederle) (Rx), Sumycin Syrup® (Apothecon);Tetralan Syrup® (Lannett); generic; (Rx)
Tetracycline HCl Fiber: 12.7 mg/23 cm Actisite® (Alza) (Rx)
Tetracycline HCl Topical solution: 2.2 mg/ml Topicycline® (Roberts) (Rx)
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