Chemistry - An aminocyclitol antibiotic obtained from Streptomyces spectabilis, spectinomycin is available as the dihydrochloride pentahydrate. It occurs as a white to pale buff, crystalline powder with pKas of 7 and 8.7. It is freely soluble in water and practically insoluble in alcohol.
Storage/Stability/Compatibility - Unless otherwise instructed by the manufacturer, spectinomycin products should be stored at room temperature (15-30°C).
Pharmacology - Spectinomycin is primarily a bacteriostatic antibiotic that inhibits protein synthesis in susceptible bacteria by binding to the 30S ribosomal subunit.
Spectinomycin has activity against a wide variety of gram positive and gram negative bacteria, including E. coli, Klebsiella, Proteus, Enterobacter, Salmonella, Streptococci, Staphylococcus and Mycoplasma. It has minimal activity against anaerobes, most strains of Pseudomonas, Chlamydia, or Treponema. In human medicine, spectinomycin is used principally for its activity against Neissiera gonorrhoeae.
Uses/Indications - Although occasionally used in dogs, cats, horses and cattle for susceptible infections, spectinomycin is only approved for use in chickens, turkeys and swine. Refer to the Dosage section below for more information on approved uses.
Pharmacokinetics - After oral administration only about 7% of the dose is absorbed, but the drug that remains in the GI tract is active. When injected SQ or IM, the drug is reportedly well absorbed with peak levels occurring in about 1 hour.
Tissue levels of absorbed drug are lower than those found in the serum. Spectinomycin does not appreciably enter the CSF or the eye and is not bound significantly to plasma proteins. It is unknown whether spectinomycin crosses the placenta or enters milk.
Absorbed drug is excreted via glomerular filtration into the urine mostly unchanged. No specific pharmacokinetic parameters were located for veterinary species.
Contraindications/Precautions/Reproductive Safety - Spectinomycin is contraindicated in patients hypersensitive to it. The reproductive safety of the drug is not known.
Adverse Effects/Warnings - When used as labeled, adverse effects are unlikely with this drug. It is reported that parenteral use of this drug is much safer than with other aminocyclitol antibiotics, but little is known regarding prolonged use of the drug. It is probably safe to say that spectinomycin is significantly less ototoxic and nephrotoxic than other commonly used aminocyclitol antibiotics, but can cause neuromuscular blockade. Parenteral calcium administration will generally reverse the blockade.
Adverse effects that have been reported in human patients receiving the drug in single or multidose studies include soreness at injection site, increases in BUN, alkaline phosphatase and SGPT, and decreases in hemoglobin, hematocrit and creatinine clearance. Although increases in BUN and decreases in creatinine clearance and urine output have been noted, overt renal toxicity has not been demonstrated with this drug.
Overdosage/Acute Toxicity - No specific information was located on oral overdoses, but because the drug is negligibly absorbed after oral administration, significant toxicity is unlikely via this route. Injected doses of 90 mg produced transient ataxia in turkey poults.
Drug Interactions - Antagonism has been reported when spectinomycin is used with chloramphenicol or tetracycline.
For susceptible infections:
a) 20 mg/kg IM tid (Robinson 1987)
b) For pneumonia: 20 mg/kg IM q8h; may cause local myositis. Insufficient data to comment on use. (Beech 1987b)
Monitoring Parameters -
1) Clinical efficacy
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Spectinomycin ;Injection 100 mg/ml 500 ml vials; Spectam ® Injectable (Rhone Merieux); (OTC) Approved for use in turkey poults and newly hatched chicks.
Spectinomycin Water Soluble Concentrate 50% Powder in 128 g (64 g spectinomycin), 200 g (100 g spectinomycin), 1000 g (500 g spectinomycin) packets; Spectam® Water Soluble Concentrate (Rhone Merieux); (OTC) Approved for use in chickens (not layers). Slaughter withdrawal = 5 days.
Spectinomycin Oral Solution 50 mg/ml in 240 ml pump bottle and 500 and 1000 ml refill bottles; Spectam Scour-Halt® (Rhone Merieux); (OTC) Approved for use in swine (Not older than 4 weeks of age or greater than 15 lbs of b.w.). Slaughter w’drawal = 21 days.
Spectinomycin Oral Solution 50 mg/ml in 240 ml pump bottle and 500 and 1000 ml refill bottles; Spectinomycin Oral Liquid (Syntex); (OTC) Approved for use in swine (Not older than 4 weeks of age or greater than 15 lbs of b.w.). Slaughter w’drawal = 21 days.
Spectinomycin combination products:
Spectinomycin/Lincomycin in a 2:1 ratio Soluble Powder
LS 50 Water Soluble Powder (Upjohn); (OTC) Approved for use in chickens. No withdrawal time required.
Spectinomycin Powder for Injection 400 mg (as the HCl) per ml after
reconstitution. 2 g vial with 3.2 ml diluent and
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