24 – Parasiticides Part II

Question 1

Piperazine

Answer 1

• Old dewormer
• *get large roundworms (ascarids)
  o No effect on migrating larvae
• Generally safe, but can cause GI upset or neuro signs
• Formulation: oral solution and tablets
• *wont use as a vet as it’s available over the counter

Question 2

Mechanism of Piperazine

Answer 2

• Anticholinergic activity ta parasite NMJ, but probably hyperpolarization of NMJ
  o Leads to flaccid paralysis

Question 3

Diethylcarbamazine (DEC)

Answer 3

• Similar to piperazine
• Heart worm prevention and ascarids

Question 4

Pyrantel (pyrimidine) mechanism

Answer 4

• Depolarizes NMJ
  o Nicotinic receptor agonists
  o Leads to spastic paralysis

Question 5

Pyrantel (pyrmidine)

Answer 5

• NEMATODES
  o Maybe cestodes?
  o Horses: resistance typical in small stronglyes
• Many solutions
• VERY SAFE (7x dose before toxic effects)

Question 6

Pyrantel formulations small animal (Pamoate)

Answer 6

• Drontal (cats), Drontal plus (dogs)
• Dolpac
• Heart-Gard plus

Question 7

Pyrantel formulations in equine (Pamoate)

Answer 7

• Exodus: oral past
• Strongid: oral past or suspension
  o Effective against large strongyles
  o Extralabel use in small animals

Question 8

Pyrantel formulation: Tartrate

Answer 8

• Pro-Banminth premix (swine)
  o Prevention of Ascaris suum

Question 9

Emodepside (Profender)

Answer 9

• Topical solution for cats
• Mechanism: induces intracellular signalling transduction in parasite pharynxe and body wall muscle
  o Flaccid paralysis
• *round, hooks and tapeworms
• VERY SAFE, including pregnant queens)
• No resistance

Question 10

Praziquantel

Answer 10

• Anti-cestode (tapeworm) drug for dogs/cats, horses, cattle
  o Minimal activity against nematodes
  o *does NOT work for cysts, just the ADULTS
• Found in combination with many anti-nematode drugs
• Can be available by itself (ex. Droncit injectable/table)
  o Expensive for big, guard dogs (use a human product $4)
• Metabolismed by CYP

Question 11

Mechanism of praziquantel

Answer 11

• Increase ICF Ca=leads to spastic paralysis

Question 12

Diphyllobothrium treatment

Answer 12

• Tapeworm from fish in N. SK
• HARD to treat!
• May require multiple treatments or increased dose
• *relatively resistant to praziquantel (Droncit)

Question 13

Praziquantel drug interaction with grape juice

Answer 13

• Inhibit CYP3A enzymes
• Inhibit P-gp transporters
• *increases bioavailability
  o Decrease intestinal and hepatic metabolism and transport before drug absorption)
• *increased half life
  o Decreased metabolism and excretion once absorbed

Question 14

Epsiprantel (Cestex tablets)

Answer 14

• Active against tapeworms in dogs and cats
• Similar to praziquantel
• Poor oral bioavailability (not an issue for tapeworms)
• Likely very safe (minimal absorption, metabolism)
  o No drug interactions noted

Question 15

Melarsomine (Immiticide: dogs only)

Answer 15

• Kills heartworm adults
• Give by injection
• *lots of side effects
• NASTY, NASTY DRUG

Question 16

Closantel (Flukiver)

Answer 16

• Oral suspension for sheep and lambs
• Label indication: treatment of Haemonchus contortus (barbe pole worm) infection
• Long withdrawal (49 days): not for lactating sheep
• Used extra-label against liver flukes in cattle and sheep (Fasciola hepatica)

Question 17

Mechanism of action of Closantel (Flukiver)

Answer 17

• Orally as a drench
• Absorbed in the blood stream and act on worms that suck on blood (Haemonchus contortus suck on abomasum)
• *does NOT get any of the other worms

Question 18

PK of Closantel (Flukiver)

Answer 18

• Decent oral bioavailability
• HIGH protein binding
• Limited tissue distribution, but that is okay

Question 19

Startech (Derquantel and abamectin)

Answer 19

• Specific for hemonchus and everything else
• *off market=can’t get bulk drug from China