Your cat has stopped eating, the vet has prescribed mirtazapine, and you want to check the number on the label against your cat's weight. So you search for a dosage chart.
Several sites will hand you one. They are answering a question the drug does not have. Mirtazapine in cats is dosed as a flat amount per cat: the published starting figure is the same 1.88 mg for a 6 lb cat as for a 16 lb one.² There is no per-pound row to look up.
Below: the published dose for each form, why it does not scale with weight, why the 3.75 mg figure still circulating is the one the evidence moved away from, how kidney and liver disease change the interval rather than the milligrams, and the mistake behind most poison-control calls.
Key takeaways
- The dose is per cat, not per pound. 1.88 mg orally is the recommended starting dose in a normal adult cat, unchanged by body weight — so exposure per kilogram runs about three and a half times higher in a 2 kg cat than a 7 kg one.²
- Disease changes the interval, not the milligrams. The same 1.88 mg goes every 24 hours normally and every 48 in an elderly or kidney-disease cat, because the half-life stretches from 9.2 to 15.2 hours.²⁴
- 3.75 mg is the superseded figure. Cats ate no more food on it than on 1.88 mg, but had significantly more behaviour changes.³
- The 15 mg human tablet is the real hazard. In 84 cats reported to the ASPCA Animal Poison Control Center, 15 mg was the dose most often associated with signs of toxicity — 40 cats, against one call for 1.88 mg.²
How much mirtazapine does a cat get?
1.88 mg by mouth, once every 24 hours, in a cat that is otherwise normal and not geriatric. That is the recommendation in a peer-reviewed review in Today's Veterinary Practice, written by the internist whose own trials produced the figure: "A starting dose of 1.88 mg orally q24h is recommended in nongeriatric, physiologically normal cats, and administration of 1.88 mg orally q48h is recommended in elderly cats, cats with CKD, and cats with liver disease."²
Three forms reach a cat, and only one is FDA-approved for this use: Mirataz, a 2% ointment dosed as "a 1.5-inch ribbon of ointment (approximately 2 mg/cat) on the inner pinna of the cat's ear once daily for 14 days," for "body weight gain in cats with a history of weight loss."¹ The oral route uses human tablets compounded down; a compounded gel is the third and least predictable.
| Form | Published dose | Interval | Regulatory status for this use |
|---|---|---|---|
| Oral mirtazapine (human tablets, split or compounded) | 1.88 mg per cat | Every 24 h normally; every 48 h in elderly cats and in kidney disease; every 48–72 h in significant liver disease² | Off-label (extra-label) use of a human drug |
| Mirataz 2% transdermal ointment | 1.5-inch ribbon, approx. 2 mg per cat¹ | Once every 24 h for 14 days, alternating ears¹ | FDA-approved for weight gain in cats with a history of weight loss |
| Compounded transdermal gel | Varies by pharmacy; the published pilot used 7.5 mg⁷ | Once every 24 h in the pilot study⁷ | Compounded; concentration accuracy is a documented concern² |
Note what the table lacks: a weight column. Every figure above is an amount per cat.
Why is there no mirtazapine dosage chart by weight for cats?
Because neither the dose nor the drug's behaviour scales. Mirtazapine "does not display linear pharmacokinetics in cats" — metabolism appears to slow at higher doses, possibly through overburdened enzyme systems.²³ A drug like that cannot be laid out on a milligram-per-kilogram grid and trusted at the ends.
The flat dose has one consequence a weight chart could usefully show: because the milligrams stay put while the cat changes, exposure per kilogram moves a great deal across normal cat sizes. The arithmetic below is the published dose divided by the weight.
| Cat weight | (kg) | Published oral starting dose | Implied exposure | Mirataz ribbon |
|---|---|---|---|---|
| 4 lb | 1.8 | 1.88 mg | ~1.04 mg/kg | Not evaluated below 2 kg¹ |
| 6 lb | 2.7 | 1.88 mg | ~0.69 mg/kg | 1.5-inch ribbon |
| 8 lb | 3.6 | 1.88 mg | ~0.52 mg/kg | 1.5-inch ribbon |
| 10 lb | 4.5 | 1.88 mg | ~0.41 mg/kg | 1.5-inch ribbon |
| 12 lb | 5.4 | 1.88 mg | ~0.35 mg/kg | 1.5-inch ribbon |
| 15 lb | 6.8 | 1.88 mg | ~0.28 mg/kg | 1.5-inch ribbon |
| 18 lb | 8.2 | 1.88 mg | ~0.23 mg/kg | 1.5-inch ribbon |
The dose column is flat; the exposure column spans more than fourfold. That is not a reason to adjust anything yourself — it is why the transdermal label says the product "has not been evaluated in cats < 2 kg or less than 6 months of age," and why a very small or young cat is a conversation with your vet, not a row on a chart.¹
The odd number has an origin: human mirtazapine comes as 15 mg tablets, and 1.88 mg is one-eighth of one. Eighths are not something to split by eye, which is why the Today's Veterinary Practice review points to "the benefit of dispensing exact doses of mirtazapine."²
What changed about the 3.75 mg dose?
It stopped being the starting dose, because a trial showed it bought nothing and cost something. In a crossover, blinded study, 14 healthy cats received placebo, 1.88 mg or 3.75 mg of oral mirtazapine. Cats on either dose ate significantly more food than on placebo — but "no difference in food ingestion was seen between HD and LD, but significantly more behavior changes were seen with the HD": increased vocalization, activity and socialization.³²
The pharmacokinetics say the same from the other direction. Median half-life was 9.2 hours at 1.88 mg and 15.9 hours at 3.75 mg in normal young cats — disproportionate between them, and "much shorter than originally postulated" in both.²³ Given daily for six days, the 1.88 mg dose produced no significant accumulation.³
So a page giving 3.75 mg, or telling you to quarter a 15 mg tablet, is not inventing a figure — it is quoting the one the evidence has since argued down. Your vet may still choose it; what changed is that it is no longer where a cat starts.
How does kidney or liver disease change the dose?
It changes the interval, not the milligrams: the same 1.88 mg, just less often, because the cat clears it more slowly.
The kidney figures come from six cats with IRIS stage 2 and 3 chronic kidney disease given a single oral 1.88 mg dose. Their mean half-life was 15.2 hours against 12.1 hours in age-matched geriatric controls, and the authors concluded that "a single low dose of mirtazapine resulted in a half-life compatible with a 48-hour dosing interval in CKD cats."⁴ Liver disease stretches it further and far less predictably: a median of 13.8 hours but a range from 7.9 to 61.4 hours, against 7.4 hours in controls — hence every 48 to 72 hours there.²
There is outcome evidence behind that interval, not just pharmacokinetics. In a placebo-controlled, double-masked crossover trial, 11 cats with stable CKD received 1.88 mg or placebo every other day for three weeks. Appetite and activity improved significantly (P=0.02 each), vomiting fell (P=0.047), and the cats gained weight against placebo (P=0.002), a median of 0.18 kg.⁵ On the drug 91% gained weight; on placebo 82% lost it.²
That trial is why mirtazapine appears so often in feline kidney disease, and why appetite belongs in a daily record rather than in memory at the appointment — the full list is in what to log for a cat with chronic kidney disease. The drug's job there is to make the prescribed food possible at all; which food, and why, is the renal diet guide.
How is the transdermal ointment dosed, and does it work as well?
By length, not by weight: a 1.5-inch ribbon, about 2 mg, rubbed onto the inner flap of one ear once a day for 14 days, alternating left and right. The label is specific about the mechanics — disposable gloves, discarded after each application, never into the ear canal, and the clinic demonstrates the first dose in front of you.¹
It works. In the randomised, vehicle-controlled field study behind the approval, 230 cats with a documented history of at least 5% weight loss were enrolled and 177 were eligible for the effectiveness analysis. At week 2, mean body weight had risen 3.94% on mirtazapine against 0.41% on vehicle (p<0.0001).¹ Those cats were 2.8 to 24.6 years old, most often with renal insufficiency, vomiting or hyperthyroidism — the population actually prescribed it.¹
Transdermal is not simply oral through the skin, though. On the inner pinna, mean relative bioavailability against the oral route was 64.9%, peak concentration came at 15.9 hours rather than 1.1, and the calculated half-life was 26.8 hours against 10.1 orally.⁶ Slower in, slower out — which is why the ointment carries its own label dose rather than borrowing the oral one.
Anyone who has fought a methimazole tablet will know the route: transdermal thyroid medication goes on the same ear flap, and the hyperthyroidism guide compares it with pilling. The compounded version is where care is needed. A pilot study of a compounded 7.5 mg gel did significantly increase appetite (P=0.003) and rate of food ingestion, activity, begging and vocalization (P=0.002 each),⁷ but the review flags "inaccuracy of commercially available gel preparations and the risk of contamination of ingredients used to manufacture compounded gels."² A measured ribbon is a different proposition from a gel of uncertain strength.
⚠️ What are the side effects, and what happens if a cat gets too much?
Mostly behavioural, dose-related, and they do not require an overdose. The Merck Veterinary Manual is explicit: with mirtazapine, "clinical signs might occur in both dogs and cats even at therapeutic dosages (when used to treat decreased appetite and unwanted behaviors)."⁹
The field study puts numbers on the common ones, against a vehicle control that was the identical ointment without the drug. Vocalization occurred in 13 of 115 treated cats (11.3%) against 2 of 115 on vehicle (1.7%); hyperactivity in 8 (7.0%) against 1 (0.9%); disorientation or ataxia in 4 (3.5%) against 2 (1.7%).¹ Vomiting and ear redness were no more common on the drug than on the vehicle — 11.3% against 13.0%, and 10.4% against 17.4% — so a cat who vomits on day three is not necessarily reacting to it.¹
An overdose is a different matter, and its shape is almost always the same: the household's own medicine, not the cat's. Among 84 cats reported to the ASPCA Animal Poison Control Center after exposure to oral mirtazapine, "the most common doses associated with signs of toxicity were 15 mg (40 cats) and 3.75 mg (25 cats); only 1 call was received for the 1.88-mg dose."² Fifteen milligrams is the standard human tablet.
Those cats showed vocalization, agitation, vomiting, an abnormal gait or ataxia, restlessness, tremors, drooling, fast breathing, a fast heart rate and lethargy — beginning 15 minutes to 3 hours after ingestion and resolving in 12 to 48 hours.² The serious concern with any serotonergic drug is serotonin syndrome, which Merck characterises as at least three of: altered mental status, agitation, nervousness, myoclonus, hyperreflexia, tremors, diarrhoea, incoordination, cardiovascular changes and fever.⁹
If your cat has swallowed a tablet — theirs or yours:
- Call now, before signs appear. Merck's guidance turns on timing: for mirtazapine, inducing vomiting is generally considered only "within 15–30 minutes" of ingestion — a window that closes while you are searching.⁹ That decision belongs to a veterinarian, not a kitchen remedy.
- Have the numbers ready. The tablet strength, how many are missing, and the clock time — those three facts drive everything that follows.
- In the US, ASPCA Animal Poison Control is on 888-426-4435, 24 hours a day, 365 days a year; a consultation fee may apply.¹⁰
- Mention every other medication the cat is on. The label contraindicates mirtazapine with, or within 14 days of, a monoamine oxidase inhibitor such as selegiline or amitraz, because of serotonin-syndrome risk.¹
One ordinary-sounding label instruction catches people out: for two hours after application, people and other animals should avoid contact with the treated cat, because mirtazapine is absorbed through skin and by mouth; residues are negligible by then.¹ A cat who sleeps on a child's bed is a reason to time the dose, not skip it.
What if you miss a dose, or can't tell whether it was given?
The label answers the first in one sentence: "If a dose is missed, apply Mirataz the following day and resume daily dosing."¹ Not a double ribbon, not a catch-up dose — the next scheduled one.
The second question is harder, and structural rather than medical. Three things stack against you. The every-other-day interval used in elderly and kidney-disease cats has no daily rhythm to hang on.² An ointment inside an ear leaves nothing visible within two hours, so you cannot inspect the cat and find out.¹ And the drug's visible effect is a cat eating — the very thing an anxious household is already watching, and will read either way.
So the answer is a record, not a reminder. A reminder says a dose is due; only a record says whether it was already given, and by whom. That is the argument in how to avoid double-dosing pet medication, and a 48-hour schedule is the version most likely to go wrong. If the trouble is getting the dose in rather than remembering it, giving a cat a pill without the fight is the more useful page.
Does mirtazapine fix the reason a cat stopped eating?
No. It buys time while someone finds out why, and the literature is blunt. There are "no medications approved specifically for the treatment of anorexia in cats," and of the agents used historically, "due to potential side effects and/or lack of efficacy or predictability only cyproheptadine and mirtazapine can currently be recommended for use."⁸ The same review notes that "most cats presenting with reduced food intake will be suffering from an underlying systemic disease," and that appetite stimulation "should never replace monitoring and ensuring adequate caloric intake."⁸
The urgency is specific to cats, which tolerate inadequate intake badly, "especially given their propensity to develop hepatic lipidosis, their increased requirements for amino acids, and inability to slow their rate of gluconeogenesis."⁸ A cat eating a little more while the cause goes unexamined is not getting better.
The label makes the point from the other end. After the 14-day course, food intake "may lessen after discontinuation," and if it drops by more than 75% for several days, or the cat stops eating for more than 48 hours, the cat needs re-evaluating.¹ The drug is a window, and the label expects you to watch through it.
Which is the thing to take away. The number everyone searches for is flat and settled: 1.88 mg, or a 1.5-inch ribbon. What changes the outcome is the record of what the cat ate, what it weighed and which days got a dose — because that is what a veterinarian adjusts against, and nobody reconstructs it from memory.
Veterinary medical disclaimer: SteadyTails is a logging and coordination tool, not a substitute for veterinary care. Nothing here is a diagnosis, a prescription or a dosing instruction. Mirtazapine is prescription-only, and every figure quoted or derived here is a label dose, a published recommendation or a study result — not an amount to give your cat. Oral use in cats is extra-label use of a human drug and must be directed by a veterinarian. Do not start, stop, repeat, skip or adjust a dose on your own judgement, and never give a human tablet to a cat. If your cat has swallowed mirtazapine, or is vocalising, agitated, trembling, unsteady, disoriented or breathing fast, contact your veterinarian or an emergency animal hospital immediately.
"Is today an ear day? And did she actually eat afterwards?"
An every-other-day ointment that leaves no trace is the hardest dose to keep straight — and what your vet needs at the recheck is what the cat ate and what it weighed. SteadyTails keeps every dose, skipped dose, meal and weight on one timeline the whole household writes to, with a name and a timestamp on each entry. Available now on the App Store • Android coming soon.
Download on the App Store →References
- U.S. Food and Drug Administration / DailyMed. Mirataz — mirtazapine transdermal ointment, Dechra Veterinary Products — "Each 1 g of Mirataz contains 20 mg mirtazapine (2%)"; "For topical application in cats only. Not for oral or ophthalmic use"; indication: "Mirataz is indicated for body weight gain in cats with a history of weight loss"; dosage: "Administer topically by applying a 1.5-inch ribbon of ointment (approximately 2 mg/cat) on the inner pinna of the cat's ear once daily for 14 days"; "Wear disposable gloves when applying Mirataz. Dispose of used gloves after each application"; "Alternate the daily application of Mirataz between the left and right inner pinna of the ears. Do not administer into the external ear canal"; "If a dose is missed, apply Mirataz the following day and resume daily dosing"; "To demonstrate the method of administering the dose, the veterinarian or trained personnel at the clinic should apply the first dose in the presence of the owner"; contraindications: "Mirataz should not be given in combination, or within 14 days before or after treatment with a monoamine oxidase inhibitor (MAOI) [e.g. selegiline hydrochloride (L-deprenyl), amitraz], as there may be an increased risk of serotonin syndrome"; human warnings: "After application, care should be taken that people or other animals in the household do not come in contact with the treated cat for 2 hours because mirtazapine can be absorbed transdermally and orally. However, negligible residues are present at the application site and the body of the cat at 2 hours after dosing"; precautions: "Do not administer orally or to the eye"; "Use with caution in cats with kidney disease. Kidney disease may cause reduced clearance of mirtazapine which may result in higher drug exposure"; "Upon discontinuation of Mirataz, it is important to monitor the cat's food intake. Food intake may lessen after discontinuation of mirtazapine transdermal ointment. If food intake diminishes dramatically (>75%) for several days, or if the cat stops eating for more than 48 hours, reevaluate the cat"; "Mirataz has not been evaluated in cats < 2 kg or less than 6 months of age"; effectiveness: "Enrolled cats were ≥ 1 year of age and had existing documented medical history of ≥ 5% weight loss deemed clinically significant. The most common pre-existing conditions included renal insufficiency, vomiting, and hyperthyroidism"; "A total of 230 cats were enrolled and received either Mirataz (115 cats) or a vehicle control (115 cats)"; "The cats were 2.8-24.6 years of age and weighed 2.1-9.2 kg"; "A total of 177 cats were determined to be eligible for the effectiveness analysis; 83 cats were in the Mirataz group and 94 cats were in the vehicle control group"; "At Week 2, the mean percent increase in body weight from Day 1 was 3.94% in the mirtazapine group and 0.41% in the vehicle control group. The difference between the two groups was significant (p<0.0001)"; adverse reactions Table 1 (Mirataz N=115 vs vehicle control N=115) — Vocalization 13 (11.3%) vs 2 (1.7%); Hyperactivity 8 (7.0%) vs 1 (0.9%); Disoriented state or ataxia 4 (3.5%) vs 2 (1.7%); Vomiting 13 (11.3%) vs 15 (13.0%); application-site Erythema 12 (10.4%) vs 20 (17.4%). dailymed.nlm.nih.gov Retrieved 2026-10-05.
- Quimby JM. Mirtazapine: Addressing Appetite in Cats, Today's Veterinary Practice (peer reviewed), March/April 2019, pp. 66–68 — "Cats receiving oral mirtazapine at 1.88 mg q24h and 3.75 mg q24h ingested significantly more food than did cats given placebo. However, significantly more side effects (increased vocalization, activity, and socialization) were seen with the higher dose, and the amount of food ingested did not differ between the dose groups. On the basis of this research, 1.88 mg is recommended as the initial starting dose for oral mirtazapine and can be given as frequently as daily in young normal cats"; "Pharmacokinetic studies in cats have shown that the median half-life of oral mirtazapine is 9.2 hours for the 1.88-mg dose and 15.9 hours for the 3.75-mg dose in normal young animals; this is much shorter than originally postulated"; "When a 1.88-mg dose was given to young normal cats daily, no significant drug accumulation occurred"; "Mirtazapine does not display linear pharmacokinetics in cats: In other words, metabolism appears slowed at higher doses, possibly because of overburdened enzyme systems"; "The most common adverse effects reported to the ASPCA Animal Poison Control Center in 84 cats intentionally or accidently exposed to oral mirtazapine included vocalization, agitation, vomiting, abnormal gait/ataxia, restlessness, tremors/trembling, hypersalivation, tachypnea, tachycardia, and lethargy. Onset of clinical signs ranged from 15 minutes to 3 hours after ingestion, and clinical signs resolved in 12 to 48 hours. The most common doses associated with signs of toxicity were 15 mg (40 cats) and 3.75 mg (25 cats); only 1 call was received for the 1.88-mg dose. These data highlight the benefit of dispensing exact doses of mirtazapine, given the frequency of accidental oral administration of a full 15-mg tablet"; "when 6 cats with IRIS (International Renal Interest Society) stage 2 and 3 CKD were administered a single oral 1.88-mg dose of mirtazapine, it had a half-life of 15.2 hours; in comparison, its half-life was 12.1 hours when administered to geriatric cats and 9.2 hours when given to young normal cats"; "Median weight gain during mirtazapine administration was 0.18 kg (range, 0 to 0.45 kg), and 91% of cats gained weight during therapy. Median weight loss during placebo administration was 0.07 kg (range, 0 to 0.34 kg), and 82% of cats lost weight"; "When administered to cats with liver disease (alanine aminotransferase [ALT] > 200 U/L or total bilirubin > 1 mg/dL), a single oral 1.88-mg dose had a median half-life of 13.8 hours (range, 7.9 to 61.4 hours) compared with 7.4 hours (range, 6.7 to 9.1 hours) in age-matched control cats"; "on the basis of this study, the clinical recommendation would be to give oral mirtazapine q48h to q72h to cats with significant liver disease"; "concerns about compounded transdermal mirtazapine include inaccuracy of commercially available gel preparations and the risk of contamination of ingredients used to manufacture compounded gels"; summary: "A starting dose of 1.88 mg orally q24h is recommended in nongeriatric, physiologically normal cats, and administration of 1.88 mg orally q48h is recommended in elderly cats, cats with CKD, and cats with liver disease. Side effects are dose related and are less likely to occur at this low dose"; "It is approved for cats at a labeled dose of 2 mg q24h. Mirtazapine has not been well studied in dogs." todaysveterinarypractice.com Retrieved 2026-10-05.
- Quimby JM, Gustafson DL, Samber BJ, Lunn KF. Studies on the pharmacokinetics and pharmacodynamics of mirtazapine in healthy young cats. J Vet Pharmacol Ther 2011;34(4):388–96 — "Blood was collected before, and at intervals up to 72 h after, oral dose of 3.75 mg (high dose: HD) or 1.88 mg (low dose: LD) of mirtazapine"; "Median half-life was 15.9 h (HD) and 9.2 h (LD)"; "Mirtazapine does not appear to display linear pharmacokinetics in cats"; "Pharmacodynamics was studied in 14 healthy cats administered placebo, LD and HD mirtazapine orally once in a crossover, blinded trial. In comparison with placebo, cats ingested significantly more food when mirtazapine was administered. No difference in food ingestion was seen between HD and LD, but significantly more behavior changes were seen with the HD"; "Mirtazapine (LD) was administered daily for 6 days with no drug accumulation detected." Cited from the published abstract via NCBI PubMed, PMID 20969604. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Quimby JM, Gustafson DL, Lunn KF. The pharmacokinetics of mirtazapine in cats with chronic kidney disease and in age-matched control cats. J Vet Intern Med 2011;25(5):985–9 — "Six CKD cats and 6 age-matched controls (AMC) were enrolled. Two CKD cats each from International Renal Interest Society (IRIS) stage II, III and IV were included"; "Blood samples were collected before and 0.5, 1, 1.5, 2, 4, 8, 24, and 48 hours after a single PO dose of 1.88 mg of mirtazapine"; "Mean age was 11 years (CKD cats) and 10.8 years (AMC cats)"; "Mean half-life ± SD was 15.2 ± 4.2 hours (CKD) and 12.1 ± 1.1 hours (AMC)"; "A Mann-Whitney test indicated statistically significant differences in AUC (P = 0.01) and CL/F (P = 0.04) between groups"; "Calculated accumulation factor for 48-hour dosing in CKD cats was 1.15"; "CKD may delay the CL/F of mirtazapine. A single low dose of mirtazapine resulted in a half-life compatible with a 48-hour dosing interval in CKD cats." Cited from the published abstract via NCBI PubMed, PMID 21985134. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Quimby JM, Lunn KF. Mirtazapine as an appetite stimulant and anti-emetic in cats with chronic kidney disease: a masked placebo-controlled crossover clinical trial. Vet J 2013;197(3):651–5 — "Eleven cats with stable CKD were randomized to receive 1.88 mg mirtazapine or placebo orally every other day for 3 weeks. After a 4 day washout period, each cat crossed over to the alternate treatment for 3 weeks"; "Compared to placebo, mirtazapine administration resulted in a statistically significant increase in appetite (P=0.02) and activity (P=0.02) and a statistically significant decrease in vomiting (P=0.047), as determined by Wilcoxon matched pairs analysis. Cats treated with mirtazapine also gained significant bodyweight compared with placebo-treated cats (P=0.002)"; "Median weight gain during mirtazapine administration was 0.18 kg (range 0-0.45 kg)"; "Mirtazapine is an effective appetite stimulant and anti-emetic for cats with CKD and could be a useful adjunct to the nutritional management of these cases." Cited from the published abstract via NCBI PubMed, PMID 23838205. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Buhles W, Quimby JM, Labelle D, Williams VS. Single and multiple dose pharmacokinetics of a novel mirtazapine transdermal ointment in cats. J Vet Pharmacol Ther 2018;41(5):644–51 — "Cats were treated once with 0.5 mg/kg of mirtazapine transdermal ointment applied topically to the inner ear pinna (treatment) or administered orally (control) and then crossed over after washout"; "In Study 1, single transdermal administration of mirtazapine resulted in mean Tmax = 15.9 hr, Cmax = 21.5 ng/mL, AUC0-24 = 100 ng*hr/mL, AUC0-∞ = 260 ng*hr/mL and calculated half-life = 26.8 hr. Single oral administration of mirtazapine resulted in mean Tmax = 1.1 hr, Cmax = 83.1 ng/mL, AUC0-24 = 377 ng*hr/mL, AUC0-∞ = 434 ng*hr/mL and calculated half-life = 10.1 hr. Mean relative bioavailability (F) of transdermal to oral dosing was 64.9%"; "Single and repeat topical doses of a novel mirtazapine transdermal ointment achieve measurable plasma concentrations in cats." Cited from the published abstract via NCBI PubMed, PMID 30004120. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Benson KK, Zajic LB, Morgan PK, Brown SR, Hansen RJ, Lunghofer PJ, Wittenburg LA, Gustafson DL, Quimby JM. Drug exposure and clinical effect of transdermal mirtazapine in healthy young cats: a pilot study. J Feline Med Surg 2017;19(10):998–1006 — "Treatments consisted of 6 days of aural 7.5 mg TMZ or placebo gel at home, and 1.88 mg mirtazapine orally once in the clinic"; "Phase I: administration of TMZ achieved measureable serum mirtazapine concentrations"; "Phase II: client-owned cats administered TMZ had a significant increase in appetite ( P = 0.003), rate of food ingestion ( P = 0.002), activity ( P = 0.002), begging ( P = 0.002) and vocalization ( P = 0.002) at home." Cited from the published abstract via NCBI PubMed, PMID 27613493. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Agnew W, Korman R. Pharmacological appetite stimulation: rational choices in the inappetent cat. J Feline Med Surg 2014;16(9):749–56 (ISFM and AAFP) — "Inappetence is a commonly encountered problem in feline medicine. Primary goals in managing the inappetent or anorectic cat are to diagnose and treat the underlying disease and reinstate adequate nutrition"; "As cats are intolerant of prolonged periods of inadequate nutritional intake, especially given their propensity to develop hepatic lipidosis, their increased requirements for amino acids, and inability to slow their rate of gluconeogenesis, symptomatic therapy and nutritional support is often required during diagnostic investigations"; "Most cats presenting with reduced food intake will be suffering from an underlying systemic disease, and so the mechanism of action, pharmacokinetics and contraindications of appetite-stimulating medications will need to be considered in each case to ensure rational use of these agents. Pharmacological appetite stimulation should never replace monitoring and ensuring adequate caloric intake, and may not be appropriate in some cases, such as critically ill or severely malnourished patients"; "While there are no medications approved specifically for the treatment of anorexia in cats, some drugs have proven efficacious in the clinical field. Although several agents have been used historically for appetite stimulation, due to potential side effects and/or lack of efficacy or predictability only cyproheptadine and mirtazapine can currently be recommended for use." Cited from the published abstract via NCBI PubMed, PMID 25146662. pubmed.ncbi.nlm.nih.gov Retrieved 2026-10-05.
- Merck Veterinary Manual. Toxicoses in Animals From Human Antidepressants, Anxiolytics, and Sleep Aids — mirtazapine: "Antagonizes presynaptic alpha-adrenergic receptors to increase norepinephrine"; "Antagonizes postsynaptic serotonin (5-HT2 and 5-HT3) receptors"; "Inhibits histamine (H1) receptors and antagonizes muscarinic receptors"; "Clinical signs might occur in both dogs and cats even at therapeutic dosages (when used to treat decreased appetite and unwanted behaviors)"; "An overdose of almost any antidepressant can result in GI signs, lethargy, ataxia, agitation, shaking, seizures, tachycardia or bradycardia, vocalization, and development of serotonin syndrome"; "If the patient is clinically normal, emesis should be induced if antidepressant ingestion happened recently—generally within 2 hours for venlafaxine and selective serotonin reuptake inhibitors (SSRIs); within 15–30 minutes for the tricyclic antidepressants mirtazapine, bupropion, and trazodone, and for the monoamine oxidase inhibitor selegiline"; "The group of clinical signs characterizing serotonin syndrome usually includes at least three of the following features: altered mental status, agitation, nervousness, myoclonus, hyperreflexia, tremors, diarrhea, incoordination, cardiovascular changes (heart rate and blood pressure), and fever"; "Cyproheptadine is a serotonin antagonist often administered for treatment." merckvetmanual.com Retrieved 2026-10-05.
- ASPCA. Animal Poison Control Center — "(888) 426-4435"; "ASPCA Poison Control is your best resource for any animal poison-related emergency, 24 hours a day, 365 days a year"; "A consultation fee may apply." aspca.org Retrieved 2026-10-05.
