This article highlights some of the new drugs marketed for use in small animals and summarizes pharmacology, dosages, adverse effects, and other key information required for safe and effective use. Also included are drugs previously approved by the FDA with added approved indications or new dosage forms.
New Products for Cats
Pregabalin
Approved Use
Pregabalin is an anxiolytic FDA-approved for use in cats with acute anxiety and signs of fear associated with transportation and visits to the clinic.
Pharmacology
Pregabalin, like gabapentin, binds to the alpha2-delta subunit of voltage-gated calcium channels, decreasing calcium influx and inhibiting subsequent release of excitatory neurotransmitters (eg, glutamate, norepinephrine, serotonin).
Contraindications
Pregabalin is contraindicated in cats hypersensitive to it or any of the inactive ingredients.
Adverse Effects
Adverse effects were uncommon (<5%) in preapproval studies. Reported adverse effects included ataxia, lethargy, emesis, anorexia, weight loss, tremor, and proprioceptive abnormality.1 Sedation may occur but typically resolves within 6 hours after administration. Hypothermia and depression are also possible.
Dosage
Pregabalin (5 mg/kg PO) can be administered to cats 1.5 hours before transportation or visiting the clinic and can be given for 2 consecutive days.1
Additional Information
Pregabalin is a schedule-V controlled substance in the United States.
New Dosage Forms for Cats
Methimazole Oral Solution
Approved Use
Methimazole oral solution is bioequivalent to the FDA-approved methimazole tablets, meaning the rate and extent of absorption of the oral solution have been demonstrated to be equivalent to the tablet form.2
Dosage
The oral solution dosage is equivalent to the tablet dosage, starting with 2.5 mg/cat every 12 hours then titrated in 2.5-mg increments every ≥3 weeks.3 The 5 mg/mL dosage form is available in 30-mL and 100-mL bottles.
Additional Information
Impermeable gloves should be worn when handling this product and hands washed after handling.
New Products for Dogs
Ilunocitinib
Approved Use
Ilunocitinib is FDA-approved to control atopic dermatitis and pruritus associated with allergic dermatitis in dogs at least 12 months of age.4
Pharmacology
Ilunocitinib is a nonselective Janus kinase (JAK) inhibitor with a high potency for JAK1, JAK2, and tyrosine kinase 2 inhibition. By inhibiting JAK, ilunocitinib inhibits the function of various proinflammatory, pruritogenic, and allergy-related cytokines.
Contraindications
Ilunocitinib is contraindicated in dogs hypersensitive to it. This drug should not be used in dogs with serious infections or that are <12 months of age. Vaccines should be up to date prior to treatment. In patients that require vaccination, ilunocitinib should be withheld for at least 28 days before and after vaccination.
Adverse Effects
Adverse effects can include nausea, vomiting, anorexia, lethargy, dermal growths, epiphora/ocular discharge, elevated liver enzymes, and weight gain.4 Ilunocitinib may increase susceptibility to development of neoplasia (benign and malignant), increase risk for infection (eg, demodicosis, respiratory infection, UTI), and exacerbate progression of subclinical or uncomplicated infection into clinical or severe infection.
Dosage
Ilunocitinib (0.6-0.8 mg/kg PO every 24 hours) can be given with or without food.4 This drug should not be administered concurrently with vaccines.
Lotilaner/Moxidectin/Praziquantel/Pyrantel Combination for Dogs
Approved Use
Lotilaner/moxidectin/praziquantel/pyrantel tablets are indicated for prevention of heartworm disease caused by Dirofilaria immitis; treatment and control of roundworms, hookworms, and tapeworms; treatment and prevention of flea infestations; and treatment and control of Ixodes scapularis (black-legged tick) and Amblyomma americanum (lone star tick) infestations in dogs ≥8 weeks of age.5
Pharmacology
Lotilaner, moxidectin, praziquantel, and pyrantel are antiparasitic agents that result in paralysis and death of susceptible parasites. Lotilaner causes prolonged neuronal hyperexcitation by inhibiting insect and acarine gamma-aminobutyric acid (GABA)-gated chloride channels in the parasite CNS. Moxidectin binds selectively to glutamate-gated chloride ion channels in invertebrate nerve and muscle cells and enhances the release of GABA at presynaptic neurons. Praziquantel is thought to disrupt the tegument of tapeworms and induce sustained muscle contractions by increasing calcium release and influx across the tegument. Pyrantel causes neuronal depolarization via binding at the nematode nicotinic cholinergic receptors, acts as a neuromuscular-blocking agent, and inhibits cholinesterase.
Contraindications
The manufacturer states there are no known contraindications; however, this product should not be used in patients hypersensitive to any of the active or inactive components.
Adverse Effects
This product was well tolerated in preapproval studies. The most common adverse effects reported were diarrhea (11%), vomiting (9.4%), lethargy (6.3%), anorexia (5.8%), and dermatitis (5.2%).5 Drugs in the isoxazoline class can cause neurologic adverse effects (eg, muscle tremors, ataxia, seizures), which have been noted in patients with and without history of neurologic disorders. Moxidectin is safe for use in dogs with the multidrug sensitivity gene (MDR1 gene, also known as ABCB1 gene) mutation (also known as ABCB1-1delta) at labeled heartworm-preventive doses.6,7
Dosage
Lotilaner (minimum, 20 mg/kg), moxidectin (minimum, 0.02 mg/kg), praziquantel (minimum, 5 mg/kg), and pyrantel (minimum, 5 mg/kg) PO can be given with food or within 30 minutes of a meal once per month.5 Dogs weighing >100 lb (45.5 kg) require a combination of chewable tablets. Year-round administration is recommended for parasite prevention or control. Intermittent use can begin at least 1 month prior to fleas and ticks becoming active and within 1 month of mosquito exposure; administration should continue for at least 1 month after the last mosquito exposure.
Torsemide
Approved Use
Torsemide is conditionally FDA-approved for concurrent use with pimobendan, spironolactone, and angiotensin-converting enzyme inhibitor therapy for the management of pulmonary edema in dogs with congestive heart failure caused by myxomatous mitral valve disease.8
Pharmacology
Torsemide is a loop diuretic that inhibits sodium and chloride reabsorption in the ascending loop of Henle, leading to diuresis via decreased water reabsorption.
Contraindications
Torsemide should not be used in dogs hypersensitive to it; with renal failure or anuria; or with severe dehydration, hypovolemia, or hypotension. This drug should not be used concurrently with other loop diuretics. Administration should be discontinued in dogs with progressive renal disease if increasing azotemia and oliguria occur during treatment.
Adverse Effects
The most common adverse effects include polyuria and polydipsia, renal insufficiency, increased BUN and serum creatinine, and urinary incontinence.8
Dosage
Torsemide (0.11-0.44 mg/kg PO every 24 hours) administration should not exceed 0.44 mg/kg per day.8 Dose adjustments should be made in 25% increments.
Additional Information
Extra-label use (ie, unapproved species, dose, route, frequency, duration) of a conditionally approved drug is prohibited by the FDA.
New Dosage Forms for Dogs
Pimobendan Oral Solution
Approved Use
Pimobendan oral solution is bioequivalent to the FDA-approved chewable tablets.9
Dosage
Pimobendan oral solution (0.25 mg/kg PO every 12 hours) should be administered directly into the mouth, not mixed into food. The 1.5 mg/mL dosage form is available in 50-mL bottles.
Updated Indications
An additional indication for treatment and control of Haemaphysalis longicornis (ie, longhorned tick) was added to several products, including fluralaner 1-month tablets, sarolaner tablets, and the combination products that contain sarolaner/moxidectin/pyrantel and afoxolaner/moxidectin/pyrantel. For cats, the combination sarolaner/selamectin topical solution has an added indication of prevention of Dipylidium caninum, which results from the product's adulticidal activity against fleas.
First Generic Approvals
First generic approvals were given for pimobendan chewable tablets (dogs) and propofol multidose vials (dogs).
Adverse Drug Effects
The FDA continues to monitor drug safety after approval is granted. Suspected adverse effects should be reported to the product’s manufacturer or the FDA (see Suggested Reading).