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ZINC
EFFICACY: Adult, inconclusive
DOCUMENTATION: Adult, fair
DOSE: Wound Healing, zinc chloride spray, topical: apply twice daily
along with magnesium hydroxide ointment for 7 days (Pastorfide et
al, 1989).
PRECAUTIONS: Take with milk or meals to prevent gastric distress
(Prod Info Orazinc®, 1990).
ADVERSE EFFECTS: Side effects observed with zinc therapy
include gastrointestinal discomfort, nausea, vomiting, headaches,
drowsiness, and metallic taste (Reynolds, 1999; Brocks et al, 1977).
Other side effects associated with high-dose oral zinc
supplementation include sideroblastic anemia (Fiske et al, 1994;
Walsh et al, 1994; Ramadurai et al, 1993), microcytic anemia
secondary to zinc-induced copper deficiency anemia (Gyorffy &
Chan, 1992), reduced laboratory indicators of immune function (Tang
et al, 1996), decreased high-density lipoprotein (Chandra, 1984),
copper deficiency, hemorrhagic gastric erosions (Moore, 1978),
lymphocytoma cutis (Komatsu et al, 1997), and progressive hepatic
failure (Lang et al, 1993). An intravenous overdose of zinc resulted in
thrombocytopenia, hypotension, cardiac arrhythmias, oliguria,
hyperamylasemia, diarrhea, jaundice, and pulmonary edema (Brocks
et al, 1977).
 INTERACTIONS: Concomitant administration of copper salts,
iron salts, dimercaptopropanesulfonic acid, editinic acid, and
penicillamine might decrease gastrointestinal zinc resorption
and enhance zinc excretion (Fachinformation Zinkit®, 1997).
Zinc administered with tetracycline, doxycycline, methacycline,
or quinolones such as ciprofloxacin, grepafloxacin, norfloxacin,
phosphate salts, sparfloxacin, temafloxacin or ofloxacin can
reduce absorption of these agents. In a four-way crossover
design study, the concurrent use of ciprofloxacin and
multivitamins with zinc resulted in a decreased absorption of
ciprofloxacin by up to 24% (Polk et al, 1989). Administration
should be separated by at least four hours (Prod Info
Raxar(TM), 1997). Tetracycline and concomitant zinc
administration resulted in decreased absorption of tetracycline
by as much as 50%. This effect may be related to chelation of
the tetracycline in the GI tract, and patients receiving zinc sulfate
therapy should receive tetracycline at separate time intervals to
avoid the interaction (Hansten & Horn, 1989; Andersson et al,
1976; Penttila et al, 1975). Norfloxacin bioavailability (as
measured by 24-hour urinary excretion) was reduced between
50% to 90% by coadministration of iron, zinc, aluminum, or
magnesium containing over-the-counter medications (Campbell
et al, 1992). Foods containing high amounts of phosphorous,
calcium, or phytate (bran, brown bread) may reduce the
absorption of oral zinc (Anon, 2000; Fachinformation
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Zinkorotat®, 1995; Pecoud et al, 1975). Caffeine and dairy foods
also reduce absorption of zinc (Pecoud et al, 1975).
REGULATORY/SAFETY INFORMATION: U.S. Food and Drug
Administration (FDA) approved for the treatment of zinc
deficiencies, Wilson's disease, and acrodermatitis enteropathica
and as an astringent to relieve minor eye irritations. FDA
Pregnancy Category A (Briggs et al, 1998). Zinc is available as
dietary supplement in the United States under the Dietary
Supplement Health and Education Act of 1994 (DSHEA).
COMPARATIVE EFFICACY: Not available.
LITERATURE REPORTS: Although controlled clinical studies
are not available, it has been suggested that oral intake or
topical application to wounds can promote healing and reduce
infection (Lansdown, 1996). In zinc deficiency, wound healing is
retarded. Acute inflammatory reactions can reduce plasma zinc
levels by causing sequestration of zinc by the liver. Increased
excretion of zinc by surgical patients can also lead to low serum
levels.
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Healing of incisional wounds was faster when incisions were treated
with zinc chloride spray followed by a magnesium hydroxidecontaining ointment than when treated with the same spray and
ointment without the mineral compounds. The abdominal and
perineal incisions of 85 obstetric and gynecologic patients were
sprayed, allowed to dry for 30 seconds, and the ointment was applied
with a tongue blade to completely cover the wound. The applications
were made twice daily, with dressing changes at each application, for
7 consecutive days. Decreases in wound length between days 1 and
4 were significantly greater, the time to total healing was shorter, and
the incidence of infection was lower in the mineral group than in the
placebo group (Pastorfide et al, 1989).
In a double-blind, controlled study of patients with leg ulcers, zinc
deficiency impaired wound healing. Twenty-seven patients were
separated into 2 groups: those with low zinc levels (less than 110
micrograms percent (mcg%)) and those with normal levels. Each
group was treated with either placebo or oral zinc sulfate 200
milligrams 3 times daily for the course of wound healing. Although all
groups had virtually identical rates of healing in the first 2 weeks of
treatment, the zinc-deficient patients taking placebo showed a
marked slowing in the rate of healing thereafter. The deficient
patients treated with zinc sulfate showed rates identical to those of
the zinc-normal patients as measured by change in wound diameter
with time until complete healing. In deficient patients, zinc stores
were restored in 3 weeks and the serum reached saturation levels of
150 mcg% in 6 weeks (Hallbook & Lanner, 1972).
A systematic evaluation of literature from 1966 to 1997 concluded
that healing of leg ulcers is not improved by oral zinc
supplementation (Wilkinson & Hawke, 1998).