Trace element (zinc)
Zinc is an essential mineral for wound healing, growth, taste and smell, and the immune system. In hospital it is added to parenteral nutrition fluids to prevent zinc deficiency in patients who cannot eat.
Also known as: sulfato de zinco, zinc sulfate, zinc, zinco
Ciprofloxacin + zinc: chelation reduces fluoroquinolone absorption.
Zinc, a divalent cation, forms insoluble chelates with fluoroquinolones in the gastrointestinal tract, reducing the oral bioavailability of ciprofloxacin — with risk of therapeutic failure in infections such as urinary or respiratory tract infections. The ciprofloxacin label recommends giving the antibiotic 2 hours before or 6 hours after zinc, iron or calcium supplements and antacids. In patients taking zinc supplements (common in acute paediatric diarrhoea, wounds or deficiency), separate the doses and, if possible, give zinc with the meal furthest from the antibiotic.
Zinc + ciprofloxacin: chelation with reduced absorption. Separate by 2–6 h.
Zinc forms complexes with ciprofloxacin in the gut.
Clinical response to antibiotic therapy.
Therapy failure, unresolved infection.
Separate dosing by at least 2 hours.
DailyMed (FDA) — approved Ciprofloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c527d138-e32c-418f-9573-a3d8a796279f ; approved Zinc (zinc sulfate) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2bd646d2-2a2a-4376-8da0-c7f08b0511ac — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Doxycycline + zinc: chelation reduces tetracycline absorption.
Tetracyclines, including doxycycline, form insoluble chelates with divalent and trivalent cations (zinc, calcium, magnesium, iron, aluminium) in the gastrointestinal tract, reducing the oral absorption and plasma concentrations of the antibiotic. The doxycycline label recommends separating zinc supplements (and other cations) by at least 2–3 hours. Warn the patient about the spacing of doses and check the times on the prescription, especially in patients taking zinc supplements during the antibiotic course.
Zinc + doxycycline: chelation with reduced absorption. Separate by 2–3 h.
Zinc chelates doxycycline, reducing its bioavailability.
Clinical response to antibiotic therapy.
Unresolved infection.
Separate dosing by at least 2 hours.
DailyMed (FDA) — approved Doxycycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=fe8cd3c6-36d6-4d92-bc5c-833cd6f9cb32 ; approved Zinc (zinc sulfate) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2bd646d2-2a2a-4376-8da0-c7f08b0511ac — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Sucralfate + zinc: sucralfate binds zinc, reducing its absorption.
Sucralfate binds cations and various drugs in the gastrointestinal tract, forming complexes that reduce absorption. Concomitant zinc supplements decrease zinc bioavailability. Administration should be separated by at least 2 hours (sucralfate usually 1 hour before meals), also spacing other oral medicines, since sucralfate interferes with many of them.
Sucralfate + zinc: sucralfate binds zinc and reduces its absorption. Separate by 2 h.
The sucralfate film binds metal cations in the stomach.
Effectiveness of zinc supplementation.
No acute symptoms; deficiency with long-term use.
Separate dosing by at least 2 hours.
DailyMed (FDA) — approved Sucralfate label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e781cc0-24ec-4028-8262-dcef9873ea1f ; approved Zinc (zinc sulfate) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2bd646d2-2a2a-4376-8da0-c7f08b0511ac — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Levothyroxine + zinc: zinc may reduce levothyroxine absorption.
Zinc, like calcium and iron, can bind levothyroxine in the gastrointestinal tract and reduce its absorption, potentially raising TSH in patients with hypothyroidism. Administration should be separated by at least 4 hours: levothyroxine fasting 30–60 minutes before breakfast, and the zinc supplement at another time of day. When zinc supplementation is started or stopped, monitor TSH and adjust the levothyroxine dose if needed.
Levothyroxine + zinc: zinc may reduce levothyroxine absorption. Separate by ≥ 4 h.
Zinc supplements may bind levothyroxine in the gut.
TSH after regimen changes.
Signs of hypothyroidism.
Separate dosing by at least 4 hours.
DailyMed (FDA) — approved Levothyroxine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c8ae9dc4-836f-4912-80d7-684fd374f40a ; approved Zinc (zinc sulfate) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2bd646d2-2a2a-4376-8da0-c7f08b0511ac — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Iron + zinc: they compete for intestinal absorption.
Iron and zinc share common intestinal transporters (e.g., DMT1, divalent metal transporters) and compete with each other for absorption when given simultaneously, especially at high doses. In patients taking combined iron and zinc supplementation (common in multiple deficiencies, pregnancy or malabsorption), absorption of both can decrease. Separate the doses (e.g., iron at breakfast and zinc at dinner) or give them at different times of day; taking them with food may reduce competition but also decreases absorption of both.
Iron + zinc: compete for intestinal absorption. Separate the doses.
Iron and zinc share intestinal transport mechanisms, reducing absorption of both when taken together.
Response to supplementation.
Persistent deficiency despite supplementation.
Separate dosing by at least 2 hours.
DailyMed (FDA) — approved Iron label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4e88a847-397b-4ddb-83d7-42c9b963a0b7 ; approved Zinc (zinc sulfate) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2bd646d2-2a2a-4376-8da0-c7f08b0511ac — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Tannins in tea and coffee reduce zinc absorption.
Separate zinc dosing from tannin-containing drinks by 1-2 hours.
EMC-UK (MHRA) — approved Zinc (zinc sulfate) SmPC: https://www.medicines.org.uk/emc/product/4930/smpc
Wholegrain phytates reduce zinc absorption.
Take zinc between meals or away from wholegrains.
EMC-UK (MHRA) — approved Zinc (zinc sulfate) SmPC: https://www.medicines.org.uk/emc/product/4930/smpc
Zinc may accumulate in severe renal impairment.
Use with caution in patients with severe renal impairment.
EMC-UK (MHRA) — approved Zinc (zinc sulfate) SmPC: https://www.medicines.org.uk/emc/product/4930/smpc
Zinc at recommended doses is safe in pregnancy.
Use recommended doses (about 11 mg/day).
Compatible with breastfeeding.
No specific additional contraception.
EMC-UK (MHRA) — approved Zinc (zinc sulfate) SmPC: https://www.medicines.org.uk/emc/product/4930/smpc
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Essential trace element, cofactor of more than 70 enzymes; facilitates wound healing, helps maintain normal growth, skin hydration and the senses of taste and smell.
Structural and catalytic enzyme cofactor: participates in the activity of carbonic anhydrase, alkaline phosphatase, lactate dehydrogenase and RNA/DNA polymerases; stabilises protein structures (zinc fingers) and modulates the immune response.
In parenteral nutrition it is given intravenously (complete bioavailability); it binds to plasma albumin, alpha-2-macroglobulin and plasma amino acids (histidine, cysteine). Distributed in muscle, bone, skin, kidney, liver, pancreas, retina and prostate.
Zinc is not significantly metabolised; it is excreted mainly in faeces (via bile and intestinal secretion) and, to a lesser extent, in urine.
Serum zinc half-life is hours to days, with a total body pool of about 2 g and slow turnover (weeks). Kinetics depend on nutritional status and renal function.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
