TRIVALENT ARSENICAL
Sodium Salt
Historically, arsenicals were used for Rx of human syphilis and metazoan diseases
KILLS 98-100% of ADULT WORMS in 21 days.
dose of 0.1 ml/lb BID 2-3 days iv is from IVMA (of CAPARSOLATE SODIUM)
Both renal and hepatic elimination are important
High doses -- Approx. 50% is excreted in 24 hours.
Therapeutic doses -- 10-15% excreted in urine within 24 hr
Normal dogs die after 4 mg/lb (8.8 mg/kg), i.v. Die within few days.
At recommended dose 4.4 mg/kg/day x 30 days, no problems observed.
0.1 ml/lb CAPARSOLATE SODIUM or 2.2 mg/kg I.V. BID for 2 days.
Dogs in poor condition -- 2.2 mg/kg SID q1d for 15 days.
TISSUE SLOUGHING and PAIN if perivascular injection
VOMITION -- without other signs, may continue therapy
PERSISTENT VOMITING, ANOREXIA or ICTERUS -- STOP Rx
May see RESPIRATORY DISTURBANCES -- Cause: anaphylactoid response? Clumping of worms in pulmonary arteries? Tissue debris? Infarction?
Large doses, Same effect as inorganic ARSENIC on CAPILLARIES and ARTIERIOLES leading to VASODILATATION and CAPILLARY DAMAGE.
GASTROINTESTINAL TRACT signs -- VOMITING, DIARRHEA may occur 4-12 hours after injection and last for HOURS to DAYS.
KIDNEY -- Casts, mild albuminuria and slight increase in BUN which is temporary.
LIVER -- May cause HEPATIC DAMAGE as severe as acute yellow atrophy. Injury generally hepatic parenchyma, other times resembles bile duct occulusion.
IMMATURE FEMALES MORE RESISTANT than males. May need to repeat treatment at intervals of a few months. Theodorides p207
LIVER and KIDNEYS must be functional. -- KEY TO SUCCESSFUL, NON-TOXIC THERAPY
Drug is EXTREMELY IRRITATING, TISSUE TOXIC, therefore, must have injection needle well seated.
IVMA RECOMMENDS ADMINISTRATION via CATHETER in jugular vein to minimize the possibility of sloughing.
Feed animal 30 minutes prior to each injection. [Merck91, p.74]
Some practitioners use vitamin C, aspirin, and glucocorticoids in an attempt to lessen the toxicity of the thiacetarsamide therapy. BUT...
Vitamin C has not been shown to be helpful in reducing hepatotoxicity.
Aspirin (acetylsalicylic acid) at the time of administration may be useful
Glucocorticoids given with the thiacetarsamide actually decrease the effectiveness of the treatment. It may be useful to give glucocorticoids a day or so later, if the animal actually has signs of reacting to the treatment.
If SEVERE OVERDOSE, try using DIMERCAPROL (BAL, British AntiLewisite), which is useful for treating some heavy metal intoxications, e.g. Arsenic, Lead, Mercury, Cadmium.
Acts by CHELATION,
Hastens elimination
Relatively non-toxic.
g. If perivascular injection --
Topical DMSO
DMSO-dexamethasone tid for several days
Used to remove microfilarial stage
Cleared for this use in dogs?? Have owner sign release.(IVMA)
Dose -- 5 mg/lb po/day until microfilariae are gone, BUT NOT LONGER THAN 15 DOSES.
Most dogs require only about 6 doses.
VOMITING, but can control with atropine pretreatment.
RESTLESSNESS and NERVOUSNESS.
Used to remove microfilarial stage
Traditional drug now used very little if at all. Hepato- and nephrotoxic
Prevent development of infective larvae
No effect against adults
Actions against microfilariae, but are hazardous -- do not use in animals with microfilariae
AVMA recommends -- 1.25 mg/lb (of base drug) per day during and 2 months following exposure to mosquitos.
If must alter dosage due to tablet size, adjust so that dose is on the high side.
Related to PIPERAZINE
RELATIVELY NON-TOXIC.
GASTROINTESTINAL IRRITATION and VOMITION in few animals
Multiple generation studies -- no evidence of problems.
SEVERE REACTIONS in dogs that have circulating microfilariae
Details elsewhere in VPH 445 notes
Kill infective larvae of D. immitis
Not recommended for removing microfilariae
HEARTGARD 90 preparation specifically for this purpose
Used po
Administered 1 time per month
Remember caution on use in COLLIES
Not as effective on tissue larvae older than 30 days! -- hence the schedule must be followed carefully.