Tetracycline Hydrochloride

(tetracycline hydrochloride)


Veterinary: Panmycin Aquadrops

Veterinary Availability:

  • A variety of concentrations that can be made into suspension.


Human: Panmycin, Achromycin-V

Human Availability:

  • Capsules: 250 mg, 500 mg (can be made into suspension)
  • Injectable: 25 mg/mL


Tetracycline Hydrochloride is derived synthetically from oxytetracycline or obtained from Streptomyces aureofaciens. As a class the tetracyclines generally act as broad-spectrum bacteriostatic agents inhibiting protein synthesis by reversibly binding to the 30S subunit of bacterial ribosome; thereby blocking access of aminoacyl-tRNA to the acceptor site on the mRNA-ribosome complex preventing the growth of susceptible bacterial organisms. They are also believed to reversibly bind to 50S ribosomes, plus altering the permeability of cytoplasmic membrane in susceptible organisms.(1)

Tetracycline hydrochloride is effective against infections caused by trachoma, rickettsiae, mycoplasma, and chlamydia, as well as Gram-positive and Gram-negative bacteria.
It is widely distributed to organs and tissues, including passing through the placenta and into the fetus of pregnant animals, but only a small amount enters the central spinal fluid. The drug is excreted into breast milk, and is eliminated unchanged primarily via glomerular filtration and may accumulate with repeated dosing in those with impaired renal function. The drug is apparently not metabolized, but excreted into the GI tract where it may become inactive after chelation with fecal material.

Tetracycline hydrochloride is known to retard fetal skeletal development in the rat. Do not use in the pregnant or nursing doe, unless benefit outweighs risk.

See Tetracyclines for additional pharmacological effects.


Used to treat wound and skin infections as well as mild respiratory infections. Active against mycoplasma. This drug is also used as prophylactic treatment following surgery or injury.

Drug Interactions or Contraindications

  • In renal insufficiency or hepatic impairment, avoid concurrent administration of other nephrotoxic or hepatotoxic drugs.
  • Tetracycline has a decreased effect when given with antacids or GI products containing aluminum, calcium, zinc, or magnesium, or with iron containing preparations (e.g., multivitamins).
  • Bacteriostatic tetracycline drugs may interfere with the bactericidal effect of the penicillins, cephalosporins, and the aminoglycosides. However, there continues to be discussion regarding whether this interaction is clinically significant.1
  • Tetracycline can increase levels/toxicity of oral digoxin.

Adverse Reactions

Blood: neutropenia, esinophyllia

CNS: intracranial hypertension

EENT: sore throat

GI: anorexia (loss of appetite)

Skin: itching

Dosage Recommendations

Tetracycline hydrochloride: 5 mg/lb to 10 mg/lb, PO, TID 4, 12, Brand name: Panmycin= .05 mL/lb to 10mL/lb  4


Tetracycline hydrochloride: 10 mg/kg to 20 mg/kg, PO, q8hr to q12hr  1, 2, 26, 29, 34, 35


Tetracycline hydrochloride: 20 mg/kg, PO, q12h 1, 26, 27, 34, 41, 44


0.1% to 0.5% feed times 14 days  1, 26, 34, 41, 44


Tetracycline capsules = 500 mg of powder mixed in 1 Liter of water 4, 12


Tetracycline: 2 mg/mL to 5 mg/mL drinking water  1, 26, 34, 41, 44

*Note: when tetracycline powder from capsules are used in the water bottle, be sure to cover the bottle as the drug is light sensitive. Mixture may be kept in the refrigerator for 3 days, changing the water bottles on the cages daily. Place one ounce per rat in the water bottle daily. Prescription/non-prescription available. Although inexpensive, treating in drinking water is not desired. Remove moist foods from diet while treating with medication in the water to encourage drinking. 4


  • Absorption of tetracycline hydrochloride may be reduced when given with food and dairy products. It is recommended that they be given 2 hours before or after giving drug.
    Some drugs are known to be better absorbed without food, but unless a rat is in a hospital environment, we realize that this is impossible for the pet rat owner. It is believed to be far more important to get the medication into the rat, even if you have to mix it in a favorite food, than to worry about whether food will hinder the medication’s absorption rate.
  • May alter gut flora. It is recommended that a probiotic also be given, such as Bene-Bac.
  • Encourage fluids unless giving medication in drinking water, then reduce moist food while treating.
  • Keep tablets in tightly closed light resistant container and store both tablets and injectable at room temperature.
  • When mixing capsules in water, keep bottle covered. Good for 3 days if stored in refrigerator.
  • It is also important to note that decomposed tetracyclines (which includes oxytetracycline) may cause potentially fatal nephrotoxicity (Fanconi’s or Fanconi’s-like syndrome); therefore, it is strongly recommended to discard any outdated (expired) or decomposed medications properly.
  1. Plumb, D. (2008). Doxycycline. Plumb’s Veterinary Drug Handbook (6th ed., p. 331). Stockholm, Wis.: PharmaVet ;.


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