- What Is Drug Used For?
- Pharmacology / Actions
- Before you take Drug
- Contraindications / Precautions / Warnings
- Adverse Effects
- Reproductive / Nursing Safety
- Overdosage / Acute Toxicity
- Drug Interactions
- How to use Drug
- Monitoring; Client Information
- Client Information
- Chemistry / Synonyms
- Storage / Stability
- Dosage Forms / Regulatory Status
NUTRITIONAL; TRACE ELEMENT
Highlights of Prescribing Information
- Metal nutritional agent that may be used for zinc deficiency, to reduce copper toxicity in susceptible dog breeds (Bedlington Terriers, West Highland White Terriers) with hepatic copper toxicosis, & treat hepatic fibrosis in dogs. Has astringent & antiseptic activity topically.
- Contraindications: None; consider obtaining zinc & copper levels before treating.
- Adverse Effects: Large doses may cause GI disturbances or hematologic abnormalities (usually hemolysis), particularly if a coexistent copper deficiency exists
- Zinc overdoses (e.g., U.S. Pennies) can be serious
What Is Drug Used For?
Zinc sulfate is used systemically as a nutritional supplement in a variety of species. Oral zinc acetate has been shown to reduce copper toxicity in susceptible dog breeds (Bedlington Terriers, West Highland White Terriers) with hepatic copper toxicosis. Zinc therapy may also be of benefit in the treatment of hepatic fibrosis in the dog. Zinc sulfate is used topically as an astringent and as a weak antiseptic both for dermatologic and ophthalmic conditions.
Pharmacology / Actions
Zinc is a necessary nutritional supplement; it is required by over 200 metalloenzymes for proper function. Enzyme systems that require zinc include alkaline phosphatase, alcohol dehydrogenase, carbonic anhydrase, and RNA polymerase. Zinc is also necessary to maintain structural integrity of cell membranes and nucleic acids. Zinc dependent physiological processes include sexual maturation and reproduction, cell growth and division, vision, night vision, wound healing, immune response, and taste acuity.
When administered orally, large doses of zinc can inhibit the absorption of copper.
About 20-30% of dietary zinc is absorbed, principally from the duodenum and ileum. Bio availability is dependent upon the food in which it is present. Phytates can chelate zinc and form insoluble complexes in an alkaline pH. Zinc is stored mostly in red and white blood cells, but is also found in the muscle, skin, bone, retina, pancreas, liver, kidney, and prostate. Elimination is primarily via the feces, but some is also excreted by the kidneys and in sweat. Zinc found in feces maybe reabsorbed in the colon.
Before you take Drug
Contraindications / Precautions / Warnings
Zinc supplementation should be carefully considered before administering to patients with copper deficiency.
Large doses may cause GI disturbances. Hematologic abnormalities (usually hemolysis) may occur with large doses or serum levels greater than 1000 mcg/dL, particularly if a coexistent copper deficiency exists. Zinc acetate or methionine maybe less irritating to the stomach. Mixing the contents of the capsule with a small amount of tuna or hamburger may minimize vomiting.
Reproductive / Nursing Safety
Although zinc deficiency during pregnancy has been associated with adverse perinatal outcomes, other studies report no such occurrences. In humans, since zinc deficiency is very rare, the routine use of zinc supplementation during pregnancy is not recommended. In humans, the FDA categorizes this drug as category C for use during pregnancy (Animal studies have shown an adverse effect on the fetus, hut there are no adequate studies in humans; or there are no animal reproduction studies and no adequate studies in humans.)
Overdosage / Acute Toxicity
Signs associated with overdoses of zinc include hemolytic anemia, hypotension, jaundice, vomiting, and pulmonary edema. Suggestions for treatment of overdoses of oral zinc include removing the source, dilution with milk or water, and chelation therapy using edetate calcium disodium (Calcium EDTA). Refer to that monograph for possible doses and usage information.
The following drug interactions have either been reported or are theoretical in humans or animals receiving zinc and may be of significance in veterinary patients:
■ COPPER: Large doses of zinc can inhibit copper absorption in the intestine; if this interaction is not desired, separate copper and zinc supplements by at least two hours
■ FLUOROQUINOLONES (e.g., enrofloxacin, ciprofloxacin): Zinc salts may reduce the oral absorption of some fluoroquinolones
■ PENICILLAMINE: May potentially inhibit zinc absorption; clinical significance is not clear
■ TETRACYCLINES: Zinc salts may chelate oral tetracycline and reduce its absorption; separate doses by at least two hours
■ URSODIOL: May potentially inhibit zinc absorption; clinical significance is not clear
How to use Drug
Drug dosage for dogs:
For adjunctive treatment and prophylaxis of hepatic copper toxicosis:
a) Initially, give a loading dose of 100 mg elemental zinc (zinc acetate used in this study) twice daily (separate doses by at least 8 hours) for about 3 months; then reduce dose to 50 mg (elemental zinc) twice daily. If animal vomits, give doses with a small piece of meat. Do not give within one hour of a meal. Monitoring of zinc levels every 2-3 months initially is recommended. Target zinc levels are 200-500 micrograms/ dl. Do not allow levels to increase higher than 1000 micrograms/dl. May require 3-6 months of therapy before significant efficacy is noted. ()
b) 5-10 mg/kg elemental zinc q12h; use high end of dosage range initially for 3 months, then 50 mg PO q12h for maintenance. Separate dosage from meals by 1 -2 hours. Zinc acetate or methionine maybe less irritating to the GI than other salts. Mixing the contents of the capsule with a small amount of tuna or hamburger may also minimize vomiting. In dogs with active copper-induced hepatitis, do not use zinc alone, but in combination with a chelator (g., D-penicillamine, trientine). Target zinc plasma levels >200 micrograms/dl but <400 micrograms/dl. Monitor levels every 2-3 months and adjust dosage as necessary. ()
c) 10 mg/kg elemental zinc (given as zinc acetate or zinc gluconate) PO twice daily. Give one hour before each meal. ()
d) 1.5-2.5 mg/kg zinc gluconate PO three times daily; 0.67 mg/kg zinc sulfate PO three times daily; or 100 mg (total dose) elemental zinc (as zinc acetate) PO twice daily. Goal is to achieve zinc plasma concentrations of 200-600 meg/ dl. After a 3-6 month loading period, dose is decreased to approximately half the original dose. Serum zinc concentrations are measured every 4-6 months. If serum level drops below 150 mcg/dl, increase dose to original level. If vomiting a problem, may mix dosage with a tablespoonful of tuna fish (in oil). ()
For hepatic fibrosis:
a) 200 mg of elemental zinc PO once daily for a 10-25 kg dog. Keep zinc plasma levels between 200-300 mcg/dl. ()
For zinc-related dermatoses:
a) Rapidly growing dogs: 10 mg/kg, day PO of zinc sulfate ()
b) For zinc-responsive dermatoses found in Siberian huskies, Alaskan malamutes, Great Danes, and Doberman pinschers: Zinc sulfate: 10 mg/kg PO with food either once daily or divided q12h. Alternatively, zinc methionine: 2 mg/kg PO once daily. Correct any dietary imbalances (high calcium and phytate). Lifetime therapy usually required. If vomiting occurs, lower dose or give with food.
For syndrome seen in puppies: Dietary corrections alone usually resolve the syndrome, but zinc supplementation as above, can expedite process. Some puppies require supplementation until maturity. ()
As an appetite stimulant:
a) 1 mg/kg of elemental zinc PO once a day ()
Drug dosage for cats:
For adjunctive therapy of severe hepatic lipidosis: a) 7-10 mg/kg PO once daily, in B-Complex mixture if possible ()
As an appetite stimulant: a) 1 mg/kg of elemental zinc PO once a day ()
Monitoring; Client Information
■ See information in individual doses above
■ Although it is best to give oral zinc acetate on an empty stomach, if vomiting occurs mix with hamburger or tuna fish to decrease this side effect
Chemistry / Synonyms
Zinc acetate occurs as white crystals or granules. It has a faint acetous odor and effloresces slightly. One gram is soluble in 2.5 mL of water or 30 mL of alcohol. Zinc acetate contains 30% elemental zinc (100 mg zinc acetate = 30 mg elemental zinc).
Zinc sulfate occurs as a colorless granular powder, small needles, or transparent prisms. It is odorless but has an astringent metallic taste. 1.67 grams are soluble in one mL of water. Zinc sulfate is insoluble in alcohol and contains 23% zinc by weight (100 mg zinc sulfate = 23 mg elemental zinc).
Zinc gluconate occurs as white or practically white powder or granules. It is soluble in water; very slightly soluble in alcohol. Zinc gluconate contains 14.3% zinc (100 mg zinc gluconate = 14.3 mg elemental zinc).
Zinc acetate may also be known as: E650, or zinci acetas dihydricus.
Zinc sulfate may also be known as: zinc sulphate; zinci sulfas, zincum sulfuricum; many trade names are available.
Storage / Stability
Store zinc acetate crystals in tight containers. Unless otherwise recommended by the manufacturer, store zinc sulfate products in tight containers at room temperature.
Dosage Forms / Regulatory Status
None as single-ingredient products for systemic use; several vitamin/ mineral supplements contain zinc, however.
Zinc Acetate is available from chemical supply houses. An oral orphan medication Galzin is available.
Zinc Injection: 1 mg/mL (as sulfate; as 4.39 mg heptahydrate or 2.46 mg anhydrous) in 10 mL and 30 mL vials; 5 mg/mL (as 21.95 mg sulfate) in 5 mL and 10 mL vials; 1 mg/mL (as 2.09 mg chloride) in 10 mL vials; Zinca-Pak (Smith and Nephew SoloPak); generic; (Rx)
Zinc Sulfate Tablets: 66 mg (15 mg zinc), 110 mg (25 mg zinc) & 200 mg (45 mg zinc); Zinc 15 and Orazinc (Mericon); generic; (OTC)
Zinc Sulfate Capsules: 220 mg (50 mg zinc); Orazinc (Mericon); Verazinc (Forest); Zinc-220 (Alto); Zincate (Paddock); generic; (Rx or OTC depending on product)
Zinc sulfate is also available in topical ophthalmic preparations.
Selections from the book: “Plumb’s Veterinary Drug Handbook. Sixth Edition”. 2008