LINCOMYCIN HCL

Chemistry - An antibiotic obtained from cultures of Streptomyces lincolnensis, lincomycin isavailable commercially as the monohydrate hydrochloride. It occurs as a white to off-white, crystalline powder that is freely soluble in water. The powder may have a faint odor and has a pKaof 7.6. The commercially available injection has a pH of 3-5.5 and occurs as a clear to slightlyyellow solution.

Storage, Stability, Compatibility

Lincomycin capsules, tablets and soluble powder should bestored at room temperature (15-30°C) in tight containers. Lincomycin injectable products should bestored at room temperature; avoid freezing.
Lincomycin HCl for injection is reportedly compatible for at least 24 hours in the following IVinfusion solutions and drugs: D5W, D5W in sodium chloride 0.9%, D10W, sodium chloride 0.9%,
Ringer's injection, amikacin sulfate, cephalothin sodium, chloramphenicol sodium succinate, cimetidine HCl, cytarabine, heparin sodium, penicillin G potassium/sodium (4 hours only), polymyxin B sulfate, tetracycline HCl, and vitamin B-complex with C.
Drugs that are reportedly incompatible with lincomycin, data conflicts, or compatibility is concentration and/or time dependent include: ampicillin sodium, carbenicillin disodium, methicillinsodium and phenytoin sodium. Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used. It is suggested to consult specialized references for more specificinformation (e.g., Handbook on Injectable Drugs by Trissel; see bibliography).

Pharmacology - LINCOMYCIN HCL

The lincosamide antibiotics lincomycin and clindamycin, share mechanisms ofaction and have similar spectrums of activity although lincomycin is usually less active againstsusceptible organisms. Complete cross-resistance occurs between the two drugs; at least partialcross-resistance occurs between the lincosamides and erythromycin. They may act as bacteriostaticor bactericidal agents, depending on the concentration of the drug at the infection site and thesusceptibility of the organism. The lincosamides are believed to act by binding to the 50S ribosomalsubunit of susceptible bacteria, thereby inhibiting peptide bond formation.
Most aerobic gram positive cocci are susceptible to the lincosamides (Strep. faecalis is not), including Staphylococcus and Streptococci. Other organisms that are generally susceptible include:
Corynebacterium diphtheriae, Nocardia asteroides, Erysepelothrix, and Mycoplasma sp..
Anaerobic bacteria that may be susceptible to the lincomycin include: Clostridium perfringens. C.tetani (not C. difficile), Bacteroides (including many strains of B. fragilis), Fusobacterium,
Peptostreptococcus, Actinomyces, and Peptococcus.

Uses, Indications

Lincomycin has dosage forms approved for use in dogs, cats, swine, and incombination with other agents for chickens. Because clindamycin is generally better absorbed, moreactive, and probably less toxic, it has largely supplanted the use of lincomycin for oral and injectabletherapy in small animals. Lincomycin is more economical however, and is still used by manyclinicians. For further information refer to the Pharmacology or Doses sections.

Pharmacokinetics - LINCOMYCIN HCL

The pharmacokinetics of lincomycin have apparently not been extensivelystudied in veterinary species. Unless otherwise noted, the following information applies to humans.
The drug is rapidly absorbed from the gut, but only about 30-40% of the total dose is absorbed.
Food both decreases the extent and the rate of absorption. Peak serum levels are attained about 2-4hour after oral dosing. IM administration gives peak levels about double those reached after oraldosing, and peak at about 30 minutes post injection.
Lincomycin is distributed into most tissues. Therapeutic levels are achieved in bone, synovial fluid, bile, pleural fluid, peritoneal fluid, skin and heart muscle. CNS levels may reach 40% of those in theserum if meninges are inflamed. Lincomycin is bound from 57-72% to plasma proteins, dependingon the drug's concentration. The drug crosses the placenta and also can be distributed into milk atconcentrations equal to those found in the plasma.
Lincomycin is partially metabolized in the liver. Unchanged drug and metabolites are excreted inthe urine, feces and bile. Half-lives can be prolonged in patients with renal or hepatic dysfunction.
The elimination half-life of lincomycin is reportedly 3-4 hours in small animals.

Contraindications, Precautions, Reproductive Safety

Although there have been case reportsof parenteral administration of lincosamides to horses, cat le and sheep, the lincosamides areconsidered to be contraindicated for use in rabbits, hamsters, guinea pigs, horses and ruminantsbecause of serious gastrointestinal effects that may occur, including death.
Lincomycin is contraindicated in patients with known hypersensitivity to it or having a preexistingmonilial infection.
Lincomycin crosses the placenta and cord blood concentrations are approximately 25% of thosefound in maternal serum. Safe use during pregnancy has not been established, but neither has thedrug been implicated in causing teratogenic effects.
Because lincomycin is distributed into milk, nursing puppies or kittens of mothers taking lincomycin may develop diarrhea.

Adverse Effects, Warnings

Adverse effects reported in dogs and cats include gastroenteritis(emesis, loose stools, and infrequently bloody diarrhea in dogs). IM injections reportedly causepain at the injection site. Rapid intravenous administration can cause hypotension and cardiopulmonary arrest.
Swine may also develop gastrointestinal disturbances while taking the medication.
Overdosage, Acute Toxicity - There is little information available regarding overdoses of thisdrug. In dogs, oral doses of up to 300 mg/kg/day for up to one year or parenterally at 60 mg/kg/dayapparently did not result in toxicity.

Drug Interactions

Kaolin (found in several over-the-counter antidiarrheal preparations) hasbeen shown to reduce the absorption of lincomycin by up to 90% if both are given concurrently. Ifboth drugs are necessary, separate doses by at least 2 hours. Because lincomycin has been associated with severe diarrheas in several species, the need for an antidiarrheal product may indicateimpending toxicity. Clindamycin absorption does not appear to be significantly altered by kaolin.
Lincomycin possesses intrinsic neuromuscular blocking activity and should be used cautiouslywith other neuromuscular blocking agents.
Drug/Laboratory Interactions - Slight increases in liver function tests (AST, ALT, Alk.
Phosph.) may occur. There is apparently not any clinical significance associated with these increases.