Z

Z



Zidovudine



zye-doe′vyoo-deen


Trade and Other Names: Retrovir


Functional Classification: Antiviral



Pharmacology and Mechanism of Action


Antiviral drug. Zidovudine (AZT) acts to inhibit the viral enzyme reverse transcriptase that prevents conversion of viral RNA into DNA. Other drugs in this class include lamivudine, didanosine, and zalcitabine.



Indications and Clinical Uses


In people, AZT is used to treat HIV (AIDS). In animals, it has been experimentally used for treatment of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infection in cats. In cats, doses of 25 mg/kg q12h IV or PO produced drug concentrations in the effective range. However, efficacy in cats has been controversial and disappointing (less effective than expected).



Precautionary Information



Adverse Reactions and Side Effects


Anemia and leucopenia have been observed in treated animals. It has not been used often in animals; therefore, a full range of potential adverse effects has not been reported.



Contraindications and Precautions


No contraindications are reported for animals.



Drug Interactions


No drug interactions have been reported in animals.



Instructions for Use


At this time, experience with using AZT for treating viral disease in animals is largely experimental or anecdotal. This drug may help some cats with FIV and may prevent persistent FeLV, but documentation of efficacy is lacking.



Patient Monitoring and Laboratory Tests


Monitor the packed-cell volume (PCV) in treated cats and perform a CBC periodically.



Formulations


AZT is available in a 10-mg/mL syrup and a 10-mg/mL injection.



Stability and Storage


Store in a tightly sealed container, protected from light, and at room temperature.



Small Animal Dosage



Cats



• 15 mg/kg q12h PO, up to 20 mg/kg q8h PO.


Large Animal Dosage


No dose has been reported for large animals.



Regulatory Information


Do not administer to animals intended for food.



Zilpaterol Hydrochloride



Zil-pat’-e-role


Trade and Other Names: Zilmax


Functional Classification: Beta-adrenergic agonist



Pharmacology and Mechanism of Action


Zilpaterol is a synthetic beta (β)-receptor adrenergic agonist. It resembles other β-agonists in some actions to produce effects similar to norepinephrine. Zilpaterol is administered to cattle, in feed, as a growth promotant, and to improve feed efficiency. Zilpaterol, like other β-adrenergic agonists, stimulate β2-adrenergic receptors in muscle and promote muscle gain with less fat. Subsequently, if fed to cattle at approved levels, zilpaterol increases feed efficiency and improves muscle weight gain. In clinical studies, it substantially increased skeletal muscle mass and cross-sectional area of individual muscles.



Indications and Clinical Uses


Zilpaterol is fed to cattle (Type A medicated feed) to improve weight gain and muscle mass. It has been approved in other countries for several years and recently has been approved for use in the US.



Precautionary Information



Adverse Reactions and Side Effects


Like other β-adrenergic agonists, zilpaterol can produce cardiovascular problems associated with increased stimulation of receptors at high doses.



Contraindications and Precautions


Severe adverse effects such as tachycardia, tremors, and muscle fasciculations have been observed in horses. Zilpaterol should not be administered to horses, and precautions should be taken to ensure that horses are not accidentally exposed to zilpaterol-treated cattle feed.


Because β-adrenergic agonists such as clenbuterol are abused in humans for the purpose of promoting muscle gain and fat loss, there is a possibility that zilpaterol also could be abused in the same manner.


Labeling should include the following information: (a) Do not allow horses or other equines access to feed containing zilpaterol. (b) Not for use in animals intended for breeding. (b) Do not use in veal calves.



Drug Interactions


Use caution when administering to animals receiving other adrenergic medications.



Instructions for Use


Zilpaterol is used to increase rate of weight gain, improve feed efficiency, and increase carcass leanness in cattle fed in confinement for slaughter during the last 20 to 40 days on feed. It should be fed continuously as the sole ration during the last 20 to 40 days on feed.



Patient Monitoring and Laboratory Tests


No specific monitoring is necessary.



Formulations


Type A medicated articles containing 21.77 g zilpaterol hydrochloride per pound.



Stability and Storage


Store in a tightly sealed container, protected from light, and at room temperature.



Small Animal Dosage



• No small animal dose is established. No established uses for small animals.


Large Animal Dosage


Do not administer to horses.


Cattle dose: 6.8 g/ton of feed to provide 60 to 90 mg zilpaterol hydrochloride per head per day.



Regulatory Information


Cattle withdrawal time for slaughter: 3 days.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Z

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