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Demeclocycline – Tetracycline Antibiotic

Demeclocycline is a tetracycline antibiotic.

Dosage and Administration


Demeclocycline hydrochloride is administered orally. Because food and/or milk reduce GI absorption of demeclocycline hydrochloride, the drug should be given 1 hour before or 2 hours after meals and/or milk. To reduce the risk of esophageal irritation and ulceration, demeclocycline hydrochloride tablets should be administered with adequate amounts of fluid and probably should not be given at bedtime or to patients with esophageal obstruction or compression.



General Adult Dosage

The usual adult dosage of demeclocycline hydrochloride is 600 mg daily administered in 2 or 4 divided doses. General Pediatric Dosage The usual dosage of demeclocycline hydrochloride for children older than 8 years of age is 6.6-13.2 mg/kg daily given in 2 or 4 divided doses. Alternatively, some clinicians recommend that such children receive 300 mg/m2 daily given in 2-4 divided doses.


The manufacturer states that uncomplicated gonorrhea in adults may be treated with an initial 600-mg dose of demeclocycline hydrochloride followed by 300 mg every 12 hours for 4 days for a total of 3 g. However, tetracyclines are not included in current US Centers for Disease Control and Prevention (CDC) guidelines for the treatment of gonorrhea and doxycycline is the preferred tetracycline for presumptive treatment of coexisting chlamydial infections in patients with gonorrhea.

Syndrome of Inappropriate Antidiuretic Hormone Secretion

In the treatment of the chronic form of the syndrome of inappropriate antidiuretic hormone secretion (SIADH), a dosage of 600 mg to 1.2 g of demeclocycline hydrochloride daily given in 3 or 4 divided doses has been effective in inhibiting the action of ADH in a dose-dependent manner. Diuresis usually occurs within 5 days after initiation of therapy and reverses within 2-6 days after discontinuation of the drug.

Dosage in Renal Impairment

If demeclocycline hydrochloride is used in patients with impaired renal function, doses and/or frequency of administration must be modified in response to the degree of renal impairment. Because usual dosage of doxycycline may be used in patients with impaired renal function, this is generally the preferred derivative when a tetracycline is indicated in these patients.


Photosensitivity reactions occur more frequently and are more severe with demeclocycline than with other currently available tetracyclines. Demeclocycline also causes a reversible, dose-related diabetes insipidus syndrome which does not occur with other currently available tetracyclines.



Approximately 60-80% of an oral dose of demeclocycline hydrochloride is absorbed from the GI tract in fasting adults. Following oral administration of tablets containing demeclocycline hydrochloride in fasting adults with normal renal function, peak serum concentrations of demeclocycline were attained within 3-4 hours and averaged 0.9-1.2 mcg/mL following a single 150-mg dose and 1.5-1.7 mcg/mL following a single 300-mg dose.

Food and/or milk reduce GI absorption of the drug by 50% or more. Because tetracyclines readily chelate divalent or trivalent cations including aluminum, calcium, iron, and magnesium, concurrent oral administration of antacids and other drugs containing these cations may also decrease oral absorption of demeclocycline hydrochloride. Of the currently available tetracyclines, demeclocycline has the greatest affinity for calcium ions.


The serum half-life of demeclocycline is 10-17 hours in adults with normal renal function and is reported to be 42-68 hours in patients with severe renal impairment. In one study in adults with normal renal function, the half-life of demeclocycline was 11 hours following a single dose and 15 hours following multiple doses. In one study in adults with normal renal function, 44% of a single 150-mg oral dose of demeclocycline hydrochloride was excreted in urine and 31% was excreted in feces within 48 hours as active drug.

Chemistry and Stability


Demeclocycline is a tetracycline antibiotic derived from a mutant strain of Streptomyces aureofaciens. Demeclocycline is commercially available as the hydrochloride salt which occurs as a yellow, crystalline powder having a bitter taste and is sparingly soluble in water and slightly soluble in alcohol.


Demeclocycline hydrochloride tablets should be stored at a controlled room temperature of 20-25°C100 in tight, light-resistant containers. For further information on chemistry and stability, mechanism of action, spectrum, resistance, pharmacokinetics, uses, cautions, drug interactions, laboratory test interferences, and dosage and administration of demeclocycline hydrochloride.


Demeclocycline Hydrochloride Powder Oral Tablets, film- 150 mg Declomycin®, coated Wyeth 300 mg Declomycin®, Wyeth

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