Doxycycline hyclate, USP is an antibacterial drug synthetically derived from oxytetracycline. The structural formula of doxycycline monohydrate is

with a molecular formula of C22H24N2O8•H2O and a molecular weight of 462.46. The chemical designation for doxycycline is 4-(Dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-2-naphthacenecarboxamide monohydrate. The molecular formula for doxycycline hydrochloride hemiethanolate hemihydrate is (C22H24N2O8•HCl)2•C2H6O•H2O and the molecular weight is 1025.89. Doxycycline hyclate is a yellow to light-yellow powder which is freely soluble in water and in methanol; sparingly soluble in alcohol; practically insoluble in chloroform and in ether. It dissolves in aqueous solutions of alkali hydroxides and carbonates.

Doxycycline has a high degree of lipoid solubility and a low affinity for calcium binding. It is highly stable in normal human serum. Doxycycline will not degrade into an epianhydro form.

Inert ingredients are microcrystalline cellulose, pregelatinized starch, hydroxypropyl cellulose, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, polyethylene glycol 6000, FD&C Blue No. 2 Aluminium Lake, and FD&C Yellow No. 6 Aluminium Lake.

FDA approved dissolution test specifications differ from USP.

Tetracyclines are readily absorbed and are bound to plasma proteins in varying degree. They are concentrated by the liver in the bile and excreted in the urine and feces at high concentrations and in a biologically active form. Doxycycline is virtually completely absorbed after oral administration.

Following a 200 mg dose, normal adult volunteers averaged peak serum levels of 2.6 mcg/mL of doxycycline at 2 hours, decreasing to 1.45 mcg/mL at 24 hours. Excretion of doxycycline by the kidney is about 40%/72 hours in individuals with normal function (creatinine clearance about 75 mL/min.). This percentage excretion may fall as low as 1 to 5%/72 hours in individuals with severe renal insufficiency (creatinine clearance below 10 mL/min). Studies have shown no significant difference in serum half-life of doxycycline (range 18 to 22 hours) in individuals with normal and severely impaired renal function.

Hemodialysis does not alter serum half-life.

Results of animal studies indicate that tetracyclines cross the placenta and are found in fetal   tissues.

Population pharmacokinetic analysis of sparse concentration-time data of doxycycline following standard of care intravenous and oral dosing in 44 pediatric patients (2 to18 years of age) showed that allometrically-scaled clearance (CL) of doxycycline in pediatric patients ≥2 to ≤8 years of age (median [range] 3.58 [2.27 to 10.82] L/h/70 kg, N =11) did not differ significantly from pediatric patients >8 to 18 years of age (3.27 [1.11 to 8.12] L/h/70 kg, N=33). For pediatric patients weighing ≤45 kg, body weight normalized doxycycline CL in those ≥2 to ≤8 years of age (median [range] 0.071 [0 .041 to 0.202] L/kg/h, N=10) did not differ significantly from those >8 to 18 years of age (0.081 [0.035 to 0.126] L/kg/h, N=8). In pediatric patients weighing >45 kg, no clinically significant differences in body weight normalized doxycycline CL were observed between those ≥2 to ≤8 years (0.05 L/kg/h, N=l) and those >8 to 18 years of age (0.044 [0.014 to 0.121] L/kg/h, N=25). No clinically significant difference in CL between oral and IV dosing was observed in the small cohort of pediatric patients who received the oral (N=19) or IV (N=2l) formulation alone.



Microbiology 

Mechanism of Action

Doxycycline inhibits bacterial protein synthesis by binding the 30S ribosomal subunit. Doxycycline has bacteriostatic activity against a broad range of Gram-positive and Gram-negative bacteria.

Resistance

Cross resistance with other tetracyclines is common.

Antimicrobial Activity

Doxycycline has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE   section of the package insert for doxycycline hyclate tablets.

Gram-Negative Bacteria

Acinetobacter species

Bartonella bacilliformis

Brucella species

Klebsiella species

Klebsiella granulomatis

Campylobacter fetus

Enterobacter aerogenes

Escherichia coli 

Francisella tularensis

Haemophilus ducreyi

Haemophilus influenzae

Neisseria gonorrhoeae

Shigella species

Vibrio cholerae

Yersinia pestis

Gram-Positive Bacteria

Bacillus anthracis

Listeria monocytogenes 

Streptococcus pneumoniae

 Anaerobic Bacteria 

Clostridium species

Fusobacterium fusiforme 

Propionibacterium acnes

 Other Bacteria 

Norcardiae and other aerobic Actinomyces species

Borrelia recurrentis

Chlamydophila psittaci

Chlamydia trachomatis

Mycoplasma pneumoniae

Rickettsiae

Treponema pallidum

Treponema pallidum subspecies pertenue

Ureaplasma urealyticum

Parasites

Balantidium coli 

Entamoeba species

Plasmodium falciparum*

*Doxycycline has been found to be active against the asexual erythrocytic forms of Plasmodium falciparum, but not against the gametocytes of P. falciparum. The precise mechanism of action of the drug is not known.

Susceptibility Testing

For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.

To reduce the development of drug-resistant bacteria and maintain effectiveness of doxycycline hyclate tablets, USP and other antibacterial drugs, doxycycline hyclate tablets, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Treatment: 

Doxycycline is indicated for the treatment of the following infections:

·         Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsialpox, and tick fevers caused by Rickettsiae.

·         Respiratory tract infections caused by Mycoplasma pneumoniae.

·         Lymphogranuloma venereum caused by Chlamydia trachomatis.

·         Psittacosis (ornithosis) caused by Chlamydophila psittaci.

·         Trachoma caused by Chlamydia trachomatis, although the infectious agent is not always eliminated, as judged by immunofluorescence.

·         Inclusion conjunctivitis caused by Chlamydia trachomatis.

·         Uncomplicated urethral, endocervical, or rectal infections in adults caused by Chlamydia trachomatis.

·         Nongonococcal urethritis caused by Ureaplasma urealyticum.

·         Relapsing fever due to Borrelia  recurrentis.

Doxycycline is also indicated for the treatment of infections caused by the following gram-negative microorganisms:

·         Chancroid caused by Haemophilus ducreyi.

·         Plague due to Yersinia pestis.

·         Tularemia due to Francisella tularensis.

·         Cholera caused by Vibrio cholerae.

·         Campylobacter fetus infections caused by Campylobacter fetus.

·         Brucellosis due to Brucella species (in conjunction with streptomycin).

·         Bartonellosis due to Bartonella bacilliformis.

·         Granuloma inguinale caused by Klebsiella granulomatis.

Because many strains of the following groups of microorganisms have been shown to be resistant to doxycycline, culture and susceptibility testing are recommended.

Doxycycline is indicated for treatment of infections caused by the following gram-negative bacteria, when bacteriologic testing indicates appropriate susceptibility to the drug:

·         Escherichia coli.

·         Enterobacter aerogenes.

·         Shigella species.

·         Acinetobacter species.

·         Respiratory tract infections caused by Haemophilus influenzae. 

·         Respiratory tract and urinary tract infections caused by Klebsiella species.

Doxycycline is indicated for treatment of infections caused by the following gram-positive microorganisms when bacteriologic testing indicates appropriate susceptibility to the drug:

·         Upper respiratory infections caused by Streptococcus pneumoniae.

·         Anthrax due to Bacillus anthracis, including inhalational anthrax (post-exposure): to reduce the incidence or progression of disease following exposure to aerosolized Bacillus anthracis.

When penicillin is contraindicated, doxycycline is an alternative drug in the treatment of the following infections:

·         Uncomplicated gonorrhea caused by Neisseria gonorrhoeae.

·         Syphilis caused by Treponema pallidum.

·         Yaws caused by Treponema pallidum subspecies pertenue.

·         Listeriosis due to Listeria monocytogenes.

·         Vincent’s infection caused by Fusobacterium fusiforme.

·         Actinomycosis caused by Actinomyces israelii.

·         Infections caused by Clostridium species.

In acute intestinal amebiasis, doxycycline may be a useful adjunct to amebicides.

In severe acne, doxycycline may be useful adjunctive therapy.

Prophylaxis: 

Doxycycline is indicated for the prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (<4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains. (See DOSAGE AND ADMINISTRATION section and Information for Patients subsection of the PRECAUTIONS section.)

This drug is contraindicated in persons who have shown hypersensitivity to any of the   tetracyclines.

The use of drugs of the tetracycline class during tooth development (last half of pregnancy, infancy and childhood to the age of 8 years) may cause permanent discoloration of the teeth (yellow-gray-brown).This adverse reaction is more common during long-term use of the drugs, but it has been observed following repeated short-term courses. Enamel hypoplasia has also been reported. Use doxycycline in pediatric patients 8 years of age or less only when the potential benefits are expected to outweigh the risks in severe or life-threatening conditions (e.g., anthrax, Rocky Mountain spotted fever), particularly when there are no alternative therapies.

Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including doxycycline hyclate tablets, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following the use of antibacterial drugs. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing use of antibacterial drugs not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

Severe skin reactions, such as exfoliative dermatitis, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) have been reported in patients receiving doxycycline. (See ADVERSE REACTIONS.) If severe skin reactions occur, doxycycline should be discontinued immediately and appropriate therapy should be instituted. 

Intracranial hypertension (IH, pseudotumor cerebri) has been associated with the use of tetracyclines including doxycycline hyclate tablets. Clinical manifestations of IH include headache, blurred vision, diplopia, and vision loss; papilledema can be found on fundoscopy. Women of childbearing age who are overweight or have a history of IH are at a greater risk for developing tetracycline associated IH. Concomitant use of isotretinoin and doxycycline hyclate tablets should be avoided because isotretinoin is also known to cause pseudotumor cerebri.

Although IH typically resolves after discontinuation of treatment, the possibility for permanent visual loss exists. If visual disturbance occurs during treatment, prompt ophthalmologic evaluation is warranted. Since intracranial pressure can remain elevated for weeks after drug cessation patients should be monitored until they stabilize.

All tetracyclines form a stable calcium complex in any bone-forming tissue. A decrease in fibula growth rate has been observed in prematures given oral tetracycline in doses of 25 mg/kg every 6 hours. This reaction was shown to be reversible when the drug was discontinued.

Results of animal studies indicate that tetracyclines cross the placenta, are found in fetal tissues, and can have toxic effects on the developing fetus (often related to retardation of skeletal development). Evidence of embryotoxicity has also been noted in animals treated early in pregnancy. If any tetracycline is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.

The antianabolic action of the tetracyclines may cause an increase in BUN. Studies to date indicate that this does not occur with the use of doxycycline in patients with impaired renal    function.

Photosensitivity manifested by an exaggerated sunburn reaction has been observed in some individuals taking tetracyclines. Patients apt to be exposed to direct sunlight or ultraviolet light should be advised that this reaction can occur with tetracycline drugs, and treatment should be discontinued at the first evidence of skin erythema.

Due to oral doxycycline’s virtually complete absorption, side effects of the lower bowel, particularly diarrhea, have been infrequent. The following adverse reactions have been observed in patients receiving tetracyclines:

Gastrointestinal: anorexia, nausea, vomiting, diarrhea, glossitis, dysphagia, enterocolitis, inflammatory lesions (with monilial overgrowth) in the anogenital region, and pancreatitis. Hepatotoxicity has been reported rarely. These reactions have been caused by both the oral and parenteral administration of tetracyclines. Superficial discoloration of the adult permanent dentition, reversible upon drug discontinuation and professional dental cleaning has been reported. Permanent tooth discoloration and enamel hypoplasia may occur with drugs of the tetracycline class when used during tooth development. (See WARNINGS.) Rare instances of esophagitis and esophageal ulcerations have been reported in patients receiving capsule and tablet forms of the drugs in the tetracycline class. Most of these patients took medications immediately before going to bed. (See DOSAGE AND ADMINISTRATION.)

Skin: toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme, skin hyperpigmentation, maculopapular and erythematous rashes. Exfoliative dermatitis has been reported but is uncommon. Photosensitivity is discussed above. (See WARNINGS.)

Renal toxicity: Rise in BUN has been reported and is apparently dose related. (See    WARNINGS.)

Immune: Hypersensitivity reactions including urticaria, angioneurotic edema, anaphylaxis, anaphylactoid purpura, serum sickness, pericarditis, exacerbation of systemic lupus erythematosus, drug reaction with eosinophilia and systemic symptoms (DRESS), and Jarisch-Herxheimer reaction has been reported in the setting of spirochete infections treated with doxycycline.

Blood: Hemolytic anemia, thrombocytopenia, neutropenia, and eosinophilia have been reported.

Other: Bulging fontanels in infants and intracranial hypertension in adults. (See WARNINGS.)

When given over prolonged periods, tetracyclines have been reported to produce brown-black microscopic discoloration of the thyroid gland. No abnormalities of thyroid function studies are known to occur.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In case of overdosage, discontinue medication, treat symptomatically and institute supportive measures. Dialysis does not alter serum half-life and thus would not be of benefit in treating cases of overdosage.

The usual dosage and frequency of administration of doxycycline differs from that of the other tetracyclines. Exceeding the recommended dosage may result in an increased incidence of side effects.

Adults:

The usual dose of oral doxycycline is 200 mg on the first day of treatment (administered 100 mg every 12 hours) followed by a maintenance dose of 100 mg/day. In the management of more severe infections (particularly chronic infections of the urinary tract), 100 mg every 12 hours is recommended.

Pediatric Patients:

For all pediatric patients weighing less than 45 kg with severe or life-threatening infections (e.g., anthrax, Rocky Mountain spotted fever), the recommended dosage is 2.2 mg/kg of body weight administered every 12 hours. Children weighing 45 kg or more should receive the adult dose. (See WARNINGS and PRECAUTIONS.)

For pediatric patients with less severe disease (greater than 8 years of age and weighing less than 45 kg), the recommended dosage schedule is 4.4 mg/kg of body weight divided into two doses on the first day of treatment, followed by a maintenance dose of 2.2 mg/kg of body weight (given as a single daily dose or divided into twice daily doses). For pediatric patients weighing over 45 kg, the usual adult dose should be used. 

The therapeutic antibacterial serum activity will usually persist for 24 hours following recommended dosage.

When used in streptococcal infections, therapy should be continued for 10   days.

Administration of adequate amounts of fluid along with capsule and tablet forms of drugs in the tetracycline class is recommended to wash down the drugs and reduce the risk of esophageal irritation and ulceration. (See ADVERSE REACTIONS.)

If gastric irritation occurs, it is recommended that doxycycline be given with food or milk. The absorption of doxycycline is not markedly influenced by simultaneous ingestion of food or milk.

Studies to date have indicated that administration of doxycycline at the usual recommended doses does not lead to excessive accumulation of doxycycline in patients with renal impairment.

Uncomplicated gonococcal infections in adults (except anorectal infections in men): 100 mg, by mouth, twice a day for 7 days. As an alternate single visit dose, administer 300 mg stat followed in one hour by a second 300 mg dose. The dose may be administered with food, including milk or carbonated beverage, as required.

Uncomplicated urethral, endocervical, or rectal infection in adults caused by Chlamydia trachomatis: 100 mg, by mouth, twice a day for 7 days.

Nongonococcal urethritis (NGU) caused by C. trachomatis or U. urealyticum: 100 mg by mouth, twice a day for 7 days.

Syphilis – early: Patients who are allergic to penicillin should be treated with doxycycline 100 mg, by mouth, twice a day for 2 weeks.

Syphilis of more than one year’s duration: Patients who are allergic to penicillin should be treated with doxycycline 100 mg, by mouth, twice a day for 4 weeks.

Acute epididymo-orchitis caused by N. gonorrhoeae: 100 mg, by mouth, twice a day for at least 10 days.

Acute epididymo-orchitis caused by C. trachomatis: 100 mg, by mouth, twice a day for at least 10 days.

For prophylaxis of malaria: For adults, the recommended dose is 100 mg daily. For children over 8 years of age, the recommended dose is 2 mg/kg given once daily up to the adult dose. Prophylaxis should begin 1 to 2 days before travel to the malarious area. Prophylaxis should be continued daily during travel in the malarious area and for 4 weeks after the traveler leaves the malarious area.

Inhalational anthrax (post-exposure):

ADULTS: 100 mg of doxycycline, by mouth, twice a day for 60 days.

CHILDREN: weighing less than 45 kg; 2.2 mg/kg of body weight, by mouth, twice a day for 60 days. Children weighing 45 kg or more should receive the adult dose.

Doxycycline hyclate tablets USP, 100 mg are available in light  orange colored, round shape, biconvex, film-coated tablets debossed with “141” on one side and “L” on other side containing doxycycline hyclate, USP equivalent to 100 mg doxycycline.

NDC 62332-353-20  Bottle of 20 tablets with child resistant closure

NDC 62332-353-50  Bottle of 50 tablets with child resistant closure

NDC 62332-353-71  Bottle of 500 tablets

Doxycycline hyclate tablets USP, 50 mg are available in light beige, round shape, biconvex, film-coated tablets debossed with “2I” on one side and plain on other side containing doxycycline hyclate, USP equivalent to 50 mg doxycycline.

NDC 62332-499-60  Bottle of 60 tablets with child resistant closure

Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Dispense in tight, light-resistant containers (USP). 

Hyperpigmentation of the thyroid has been produced by members of the tetracycline class in the following species: in rats by oxytetracycline, doxycycline, tetracycline PO4, and methacycline; in minipigs by doxycycline, minocycline, tetracycline PO4, and methacycline; in dogs by doxycycline and minocycline; in monkeys by minocycline.

Minocycline, tetracycline PO4, methacycline, doxycycline, tetracycline base, oxytetracycline HCl, and tetracycline HCl were goitrogenic in rats fed a low iodine diet. This goitrogenic effect was   accompanied by high radioactive iodine uptake. Administration of minocycline also produced a large goiter with high radioiodine uptake in rats fed a relatively high iodine   diet.

Treatment of various animal species with this class of drugs has also resulted in the induction of thyroid hyperplasia in the following: in rats and dogs (minocycline); in chickens (chlortetracycline); and in rats and mice (oxytetracycline). Adrenal gland hyperplasia has been observed in goats and rats treated with oxytetracycline.

For more information call Alembic Pharmaceuticals Limited at 1-866-210-9797.

1.      Friedman JM and Polifka JE. Teratogenic Effects of Drugs. A Resource for Clinicians (TERIS). Baltimore, MD: The Johns Hopkins University Press, 2000: 149–195.

2.      Cziezel AE and Rockenbauer M. Teratogenic study of doxycycline. Obstet Gynecol 1997; 89: 524–528.

3.  Horne HW Jr and Kundsin RB. The role of mycoplasma among 81 consecutive pregnancies: a prospective study. Int J Fertil 1980; 25: 315–317.

4.  Hale T. Medications and Mothers Milk. 9th edition. Amarillo, TX: Pharmasoft Publishing, 2000: 225–226.

Manufactured by:

Alembic Pharmaceuticals Limited

(Formulation Division),

Panelav 389350, Gujarat, India

Manufactured for:

Alembic Pharmaceuticals, Inc.

Bedminster, NJ 07921, USA

Revised: 08/2021

NDC 62332-353-20 

Doxycycline Hyclate

Tablets, USP

100 mg*

Rx only

20 Tablets

Alembic

NDC 62332-499-60 

Doxycycline Hyclate

Tablets, USP

50 mg*

Rx only

60 Tablets

Alembic