Doxycycline

Doxycycline belongs to the pharmacological class of Tetracycline antibiotics.

Doxycycline has been approved to relieve symptoms and also for the treatment and maintenance of Acne vulgaris, inflammatory, moderate to severe, Actinomycosis, Anaplasmosis and ehrlichiosis, Anthrax, Bartonella spp. infection, Bite wound infection, prophylaxis or treatment, Brucellosis, Cholera, treatment, Chronic obstructive pulmonary disease, acute exacerbation, Endocarditis prophylaxis, dental or invasive respiratory tract procedure, Hidradenitis suppurativa, Lyme disease, Malaria, Otitis media, acute, Periodontitis, severe, plaque-associated, Plague, Pleurodesis, chemical, Pneumonia, community-acquired, empiric therapy, Prosthetic joint infection, Q fever, Rhinosinusitis, acute bacterial, Rocky Mountain spotted fever, Rosacea, Sexually transmitted infections, Skin and soft tissue infection, Surgical prophylaxis, uterine evacuation, Tularemia.

Doxycycline is a tetracycline antibiotic with a bioavailability of 95-100% after oral administration. It is primarily eliminated via the gastrointestinal tract, and the elimination half-life is approximately 18-22 hours in healthy adults. The drug is found to be extensively distributed throughout the body tissues, including bone and synovial fluid, with a volume of distribution of 1.5-2.5 L/kg. The maximum plasma concentration (Cmax) of doxycycline is achieved 2-4 hours after oral administration, and the bioavailability is not significantly affected by food intake. The drug is 90-100% protein-bound in plasma, mainly to albumin. The elimination of doxycycline is primarily via the fecal route, with approximately 40% of an oral dose excreted in the feces and 20-30% in the urine.

The common side effects involved in using Doxycycline are Diarrhea, Nausea, Vomiting, Abdominal pain, Headache, Dizziness, Rash, yellowness of teeth and Itching.

Doxycycline is available in the form of Capsule, Solution, reconstituted powder for IV: Syrup, Oral suspension, Tablet, Tablet, delayed-release, Capsule, delayed-release ,Periodontal extended-release liquid.

Doxycycline is approved in Germany, Japan, Malaysia, India, the U.K., the U.S, and China.

Doxycycline belongs to the pharmacological class of Tetracycline antibiotics.

Doxycycline plays a crucial role in the survival and functioning of cells, particularly bacteria, by inhibiting their protein synthesis through an allosteric binding mechanism with the 30S prokaryotic ribosomal subunit. This binding action prevents the charged aminoacyl-tRNA from associating with the A site on the mRNA-ribosome complex, thereby halting the elongation phase of protein synthesis and impeding the production of essential proteins required for bacterial survival and functioning.

In addition to its protein synthesis inhibiting properties, doxycycline also exhibits anti-inflammatory effects. It prevents calcium-dependent microtubular assembly and lymphocytic proliferation, which are crucial factors for leukocyte movement during inflammation. Additionally, doxycycline inhibits nitric oxide synthase, an enzyme responsible for the production of inflammatory signaling molecule nitric oxide.

Doxycycline has been approved to relieve symptoms and also for the treatment and maintenance of Bite wound infection, treatment, Acne vulgaris, inflammatory, moderate to severe, Actinomycosis, Anaplasmosis and ehrlichiosis, Anthrax, Bartonella spp. infection, Bite wound infection, prophylaxis or treatment, Brucellosis, Cholera, treatment, Chronic obstructive pulmonary disease, acute exacerbation, Endocarditis prophylaxis, dental or invasive respiratory tract procedure, Hidradenitis suppurativa, Lyme disease, Malaria, Otitis media, acute, Periodontitis, severe, plaque-associated, Plague, Pleurodesis, chemical, Pneumonia, community-acquired, empiric therapy, Prosthetic joint infection, Q fever, Rhinosinusitis, acute bacterial, Rocky Mountain spotted fever, Rosacea, Sexually transmitted infections, Skin and soft tissue infection, Surgical prophylaxis, uterine evacuation, Tularemia.

The maximum concentration (Cmax) as well as time to reach it (Tmax) of doxycycline may vary depending on the formulation and mode of administration. Generally, the oral immediate-release formulation of doxycycline has a Tmax of 1-3 hours, while the extended-release formulation has a Tmax of 3-5 hours. The Cmax of doxycycline after a single oral dose of immediate-release formulation ranges from 2-4 mcg/mL, while that of extended-release formulation ranges from 1.5-2.2 mcg/mL.

The onset of action of doxycycline may also vary depending on the indication being treated. For example, in the case of bacterial infections, doxycycline may start to exert its antibacterial effects within a few hours to days of initiation of treatment, depending on the severity of the infection.

The duration of action of doxycycline may also vary depending on the formulation and dose. Generally, the immediate-release formulation of doxycycline has a half-life of 18-22 hours, while the extended-release formulation has a half-life of 16-18 hours. This means that doxycycline can remain in the body for an extended period of time, allowing for less frequent dosing schedules.

Doxycycline is found to be available in the form of Capsule, Solution, reconstituted powder for IV: Syrup, Oral suspension, Tablet, Tablet, delayed-release, Capsule, delayed-release ,Periodontal extended-release liquid.

Doxycycline can be used in the following treatment:

• Acne vulgaris, inflammatory, moderate to severe
• Actinomycosis
• Anaplasmosis and ehrlichiosis
• Anthrax
• Bartonella spp. infection
• Bite wound infection, prophylaxis or treatment
• Brucellosis
• Cholera, treatment
• Chronic obstructive pulmonary disease, acute exacerbation
• Endocarditis prophylaxis, dental or invasive respiratory tract procedure
• Hidradenitis suppurativa
• Lyme disease
• Malaria
• Otitis media, acute
• Periodontitis, severe, plaque-associated
• Plague
• Pleurodesis, chemical
• Pneumonia, community-acquired, empiric therapy
• Prosthetic joint infection
• Q fever
• Rhinosinusitis, acute bacterial
• Rocky Mountain spotted fever
• Rosacea
• Sexually transmitted infections

Doxycycline can help to relieve symptoms and also for the treatment and maintenance of Acne vulgaris, inflammatory, moderate to severe, Actinomycosis, Anaplasmosis and ehrlichiosis, Anthrax, Bartonella spp. infection, Bite wound infection, prophylaxis or treatment, Brucellosis, Cholera, treatment, Chronic obstructive pulmonary disease, acute exacerbation, Endocarditis prophylaxis, dental or invasive respiratory tract procedure, Hidradenitis suppurativa, Lyme disease, Malaria, Otitis media, acute, Periodontitis, severe, plaque-associated, Plague, Pleurodesis, chemical, Pneumonia, community-acquired, empiric therapy, Prosthetic joint infection, Q fever, Rhinosinusitis, acute bacterial, Rocky Mountain spotted fever, Rosacea, Sexually transmitted infections, Skin and soft tissue infection, Surgical prophylaxis, uterine evacuation, Tularemia.

Doxycycline is approved for use in the following clinical indications:

• Acne vulgaris, inflammatory, moderate to severe
• Actinomycosis
• Anaplasmosis and ehrlichiosis
• Anthrax
• Bartonella spp. infection
• Bite wound infection, prophylaxis or treatment
• Brucellosis
• Cholera, treatment
• Chronic obstructive pulmonary disease, acute exacerbation
• Endocarditis prophylaxis, dental or invasive respiratory tract procedure
• Hidradenitis suppurativa
• Lyme disease
• Malaria
• Otitis media, acute
• Periodontitis, severe, plaque-associated
• Plague
• Pleurodesis, chemical
• Pneumonia, community-acquired, empiric therapy
• Prosthetic joint infection
• Q fever
• Rhinosinusitis, acute bacterial
• Rocky Mountain spotted fever
• Rosacea
• Sexually transmitted infections
• Skin and soft tissue infection
• Surgical prophylaxis, uterine evacuation
• Tularemia

• Acne vulgaris, inflammatory, moderate to severe: The recommended dose for doxycycline for the treatment of inflammatory acne is 50-100mg once daily, with a maximum daily dose of 200mg. The duration of therapy depends on the severity of the acne, but treatment for at least 3 months is usually required.
• Actinomycosis: The recommended dose of doxycycline for actinomycosis is 100mg twice daily for at least 6 months. In severe cases, the dose may be increased to 200mg twice daily.
• Anaplasmosis and ehrlichiosis: The recommended dose of doxycycline for anaplasmosis and ehrlichiosis is 100mg twice daily for at least 7-10 days.
• Anthrax: The recommended dose of doxycycline for the treatment of anthrax is 100mg twice daily for 60 days. The duration of treatment may be extended in severe cases.
• Bartonella spp. infection: The recommended dose of doxycycline for Bartonella spp. infection is 100mg twice daily for at least 6 weeks.
• Bite wound infection, prophylaxis or treatment: The recommended dose of doxycycline for prophylaxis of bite wound infection is 200mg as a single dose. For the treatment of an established infection, the recommended dose is 100mg twice daily for at least 7-10 days.
• Brucellosis: The recommended dose of doxycycline for brucellosis is 100mg twice daily for 6 weeks, in combination with another antibiotic such as streptomycin or rifampin.
• Cholera, treatment: The recommended dose of doxycycline for the treatment of cholera is 300mg on the first day, followed by 200mg daily for 2-5 days.
• Chronic obstructive pulmonary disease, acute exacerbation: The recommended dose of doxycycline for acute exacerbation of COPD is 100mg twice daily for at least 7-10 days.
• Endocarditis prophylaxis, dental or invasive respiratory tract procedure: The recommended dose of doxycycline for endocarditis prophylaxis is a single dose of 100mg given 1 hour before the procedure.
• Hidradenitis suppurativa: The recommended dose of doxycycline for the treatment of hidradenitis suppurativa is 100mg twice daily for at least 3 months.
• Lyme disease: The recommended dose of doxycycline for early Lyme disease is 100mg twice daily for 14-21 days. For late Lyme disease, the recommended dose is 100mg twice daily for at least 21 days.
• Malaria: The recommended dose of doxycycline for the prophylaxis of malaria is 100mg once daily, starting 1-2 days before travel and continuing for 4 weeks after leaving the malaria-endemic area. For the treatment of malaria, the recommended dose is 100mg twice daily for 7 days.
• Otitis media, acute: The recommended dose of doxycycline for acute otitis media is 100mg twice daily for at least 7-10 days.
• Periodontitis, severe, plaque-associated: The recommended dose of doxycycline for the treatment of severe, plaque-associated periodontitis is 100mg twice daily for at least 3 months.
• Pleurodesis, chemical: Doxycycline is sometimes used in pleurodesis, a procedure in which the pleural space (the space between the lungs as well as chest wall) is sealed to prevent the buildup of fluid or air. The typical dosage is 500 mg to 1 g of doxycycline administered via chest tube, with the exact dosage depending on the patient's weight and other factors.
• Pneumonia, community-acquired, empiric therapy: Community-acquired pneumonia (CAP) is a type of pneumonia that is contracted outside of healthcare settings. Empiric therapy refers to treatment that is given based on the likely cause of the illness, rather than waiting for laboratory confirmation. For CAP, the recommended doxycycline dosage is 100 mg orally or intravenously twice a day for 7-10 days. This dosage may vary depending on the severity of the illness, the patient's age and other factors.
• Prosthetic joint infection: Infection of a prosthetic joint is a serious complication that can occur after joint replacement surgery. Doxycycline is not a first-line treatment for this condition, but it may be used as an adjunct therapy in combination with other antibiotics. The dosage of doxycycline will depend on the severity of the infection and the patient's weight, but is typically around 100 mg twice a day for several weeks.
• Q fever: Q fever is a bacterial infection that can cause a wide range of symptoms, including fever, headache, and muscle aches. The recommended doxycycline dosage for Q fever is 100 mg twice a day for 14-21 days. For more severe infections, higher doses may be necessary.
• Rhinosinusitis, acute bacterial: Acute bacterial rhinosinusitis is a bacterial infection of the sinuses that can cause symptoms such as facial pain, nasal congestion, and headache. The recommended doxycycline dosage for acute bacterial rhinosinusitis is 100 mg orally twice a day for 7-14 days.
• Rocky Mountain spotted fever: Rocky Mountain spotted fever is a bacterial infection that is transmitted through tick bites. The recommended doxycycline dosage for Rocky Mountain spotted fever is 100 mg orally or intravenously twice a day for 7-14 days. In severe cases, hospitalization and intravenous administration of the drug may be necessary.
• Rosacea: Rosacea is a chronic skin condition that can cause redness, pimples, and other symptoms on the face. The recommended doxycycline dosage for rosacea is 40 mg to 100 mg orally once a day. The duration of treatment may vary depending on the severity of the condition and the patient's response to therapy.
• Sexually transmitted infections: Doxycycline is often used to treat sexually transmitted infections (STIs) such as chlamydia and gonorrhea. The recommended dosage for chlamydia is 100 mg orally twice a day for 7 days, while the recommended dosage for gonorrhea is 100 mg orally twice a day for 7 days in combination with an injection of a different antibiotic.
• Skin and soft tissue infection: Doxycycline is often used to treat skin and soft tissue infections caused by bacteria, including community-acquired cellulitis and MRSA. The recommended doxycycline dosage for skin and soft tissue infections is typically 100 mg orally twice a day for 7-10 days, but the exact dosage and duration of treatment may vary depending on the severity of the infection and other factors.
• Surgical prophylaxis, uterine evacuation: Doxycycline is not a first-line agent for surgical prophylaxis, but it may be used in certain situations, such as in patients who are allergic to other antibiotics or when other antibiotics are contraindicated. The typical dosage is a single oral dose of 200 mg administered one hour before the procedure.
• Tularemia: Tularemia is a rare infectious disease caused by the bacterium Francisella tularensis. Doxycycline is one of the preferred antibiotics for the treatment of tularemia. The recommended dosage for adults is 100 mg orally twice a day for 10-14 days. In severe cases, the duration of therapy may need to be extended. It is important to note that doxycycline should not be used as monotherapy in the treatment of tularemia, and other antibiotics may be needed in combination depending on the severity of the infection. Additionally, if the patient is pregnant or breastfeeding, other antibiotics may be preferred.

• Capsule: 50mg, 75mg, 100mg, 150mg
• Solution, reconstituted powder for IV: 100mg
• Syrup: 50mg/5mL
• Oral suspension: 25mg/5mL
• Tablet: 20mg, 50mg, 75mg, 100mg, 150mg
• Tablet, delayed-release: 50mg, 60mg, 75mg, 100mg, 120mg, 150mg, 200mg
• Capsule, delayed-release: 40mg
• Periodontal extended-release liquid: 10%

Capsule, Solution, reconstituted powder for IV: Syrup, Oral suspension, Tablet, Tablet, delayed-release, Capsule, delayed-release ,Periodontal extended-release liquid.

• Dosage Adjustments in Kidney Patients:

If the creatinine clearance (CrCl) is greater than 30 mL/min/1.73 m², no dosage adjustment is required for Doxycycline. For patients with CrCl less than 30 mL/min/1.73 m² and end-stage renal disease (ESRD), the recommended dosage of Doxycycline is 500 mg per day administered intravenously. In patients receiving dialysis, the recommended dosage is 500 mg per day administered intravenously, if Doxycycline is given less than or equal to 6 hours before dialysis, a supplemental dose of 150 mg should be given after dialysis.

• Dosage Adjustments in Pediatric Patients:

Acne vulgaris, moderate to severe, treatment:

• Children over 8 years old: 1-2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Anthrax:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 200mg/day

Brucellosis:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Chlamydial infections, uncomplicated:

• Children over 8 years old: 4.4 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Cholera, treatment:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 300mg/day

Endocarditis, prophylaxis before invasive dental procedures:

• Children over 8 years old: 4.4 mg/kg as a single dose
• Maximum dose: 300mg

Lyme disease:

• Children over 8 years old: 4.4 mg/kg/day divided into 2 doses
• Maximum daily dose: 200mg/day

Malaria:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Pneumonia, community-acquired; presumed or proven atypical infection:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Q fever:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Skin/soft tissue infections; MRSA or community-acquired cellulitis:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses
• Maximum daily dose: 100mg/day

Tickborne rickettsial disease, ehrlichiosis, or anaplasmosis:

• Children over 8 years old: 2.2 mg/kg/day divided into 1-2 doses

• Maximum daily dose: 100mg/day

There are no specific dietary restrictions related to the use of doxycycline. However, like with most antibiotics, it is generally recommended to take doxycycline with a full glass of water and to avoid taking it with milk or other dairy products as they may decrease the absorption of the medication. Additionally, taking doxycycline with food can help minimize the risk of gastrointestinal upset.

Doxycycline may be contraindicated under the following conditions:

• Patients who have a known hypersensitivity to any component of Doxycycline or to other drugs in the same class.

The physician should closely monitor the patients and keep pharmacovigilance as follows:

Tooth Discoloration and Enamel Hypoplasia

• Use of Tetracycline class drugs during the last half of pregnancy, infancy, and childhood to the age of 8 years may cause permanent discoloration of the teeth and enamel hypoplasia.

Pseudomembranous Colitis

• Antibacterial agents, including Doxycycline tablets, may cause C. difficile-associated diarrhea (CDAD), ranging in severity from mild to fatal colitis.
• CDAD must be considered in all patients who present with diarrhea following antibiotic use.

Photosensitivity

• Photosensitivity manifested by an exaggerated sunburn reaction may occur in some individuals taking tetracyclines.
• Patients exposed to direct sunlight or ultraviolet light should be advised, and treatment should be discontinued at the first evidence of skin erythema.

Superinfection

• Use of doxycycline may result in overgrowth of non-susceptible organisms, including fungi.
• Appropriate therapy should be instituted if superinfection occurs.

Benign Intracranial Hypertension

• Bulging fontanels in the infants and the benign intracranial hypertension in adults had been reported in individuals receiving tetracyclines.
• These conditions disappeared when the drug had been discontinued.

Growth and Development

• All tetracyclines forms a stable calcium complex in any bone-forming tissue, and toxic effects on the developing fetus have been observed in animals treated early in pregnancy.
• Patients using tetracyclines during pregnancy should be aware of potential hazards to the fetus.

Antianabolic Action and Laboratory Monitoring

• The antianabolic action of the tetracyclines might cause an increase in BUN.
• In long-term therapy, periodic laboratory evaluation of the organ systems, including hematopoietic, renal, and hepatic studies should be performed.

Malaria and Development of Drug Resistant Bacteria

• Doxycycline offers substantial but not complete suppression of the asexual blood stages of Plasmodium strains.
• Prescribing Doxycycline in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication increases the risk of developing drug-resistant bacteria.

Syphilis Testing

• In venereal disease when coexistent syphilis is suspected, dark-field examinations should be done before treatment is started, and blood serology repeated monthly for at least 4 months.

Incision and Drainage

• Incision and drainage or other surgical procedures should be performed in conjunction with antibiotic therapy when indicated.

It is generally recommended to avoid consuming alcohol while taking doxycycline. Alcohol consumption may increase the risk of certain side effects of the medication, such as stomach upset, nausea, and dizziness. Additionally, alcohol can reduce the effectiveness of doxycycline in treating infections.

Tetracyclines, including doxycycline, can be excreted in human milk, but the degree of absorption by breastfed infants is unclear. Short-term usage of doxycycline by lactating women is not necessarily contraindicated, but the impact of prolonged exposure to the drug through breast milk is unknown. Due to the possibility of severe adverse reactions in nursing infants from doxycycline, a decision should be made based on the significance of the drug to the mother, whether to discontinue nursing or to discontinue the drug.

Pregnancy Category D:

There is a lack of adequate as well as well-controlled studies on the use of doxycycline in pregnant women. The majority of reported cases of doxycycline use during human pregnancy involve short-term exposure during the first trimester. There is insufficient human data available to fully evaluate the effects of long-term therapy with doxycycline during pregnancy, particularly for the treatment of anthrax exposure. However, an expert review by TERIS, the Teratogen Information System, found that while the quantity and quality of data is limited to fair, therapeutic doses of doxycycline during pregnancy are unlikely to pose a significant teratogenic risk. Nonetheless, it cannot be conclusively stated that there is no risk.

A case-control study involving 18,515 mothers of infants with congenital anomalies and 32,804 mothers of infants without congenital anomalies revealed a weak but marginally significant association between the use of doxycycline during pregnancy and total malformations. However, this association was not observed when the analysis was limited to maternal treatment during the period of organogenesis (i.e., the second and third months of gestation), except for a marginal relationship with neural tube defect based on only two exposed cases.

Furthermore, a small prospective study of 81 pregnancies described 43 pregnant women who were treated with doxycycline for 10 days during the early first trimester. All the mothers reported that their exposed infants were normal at 1 year of age.

There are no specific food restrictions when taking doxycycline. However, taking the medication with food or a glass of milk can help reduce the risk of stomach upset. It is important to avoid taking doxycycline with calcium-rich foods, such as dairy products, as calcium can interfere with the absorption of the medication. Additionally, taking doxycycline with foods or drinks high in acidity, such as citrus fruits and juices, may also decrease the absorption of the medication. It is recommended to take doxycycline with a full glass of water as well as to avoid lying down for at least thirty minutes after taking the medication to reduce the risk of esophageal irritation.

The adverse reactions related to Doxycycline can be categorized as follows:

Common

• Nausea and vomiting
• Diarrhea
• Abdominal pain
• Loss of appetite
• Skin rash
• Photosensitivity (sensitivity to sunlight)
• Tooth discoloration in children under eight years of age

Less Common

• Headache
• Dizziness
• Blurred vision
• Yeast infections
• Vaginal itching or discharge
• Swelling of the tongue or throat
• Difficulty swallowing

Rare

• Hepatitis (inflammation of the liver)
• Pancreatitis (inflammation of the pancreas)
• Blood disorders (such as anemia, thrombocytopenia, and eosinophilia)
• Kidney damage or failure
• Increased intracranial pressure (pressure inside the skull).

The clinically relevant drug interactions of Doxycycline are briefly summarized here:

• Anticoagulant Drugs:

Tetracyclines have been found to reduce plasma prothrombin activity. As a result, patients who are on anticoagulant therapy may require a lower anticoagulant dose.

• Penicillin:

Bacteriostatic drugs might interfere with the bactericidal action of penicillin. Therefore, it is recommended to avoid administering tetracyclines along with penicillin.

• Antacids and Iron Preparations:

The absorption of tetracyclines is hindered by antacids that contain aluminum, calcium, or magnesium, bismuth subsalicylate, and iron-containing preparations.

• Oral Contraceptives:

Concurrent use of tetracycline may reduce the effectiveness of oral contraceptives.

• Barbiturates and Anti-Epileptics:

The half-life of doxycycline is reduced by barbiturates, carbamazepine, and phenytoin.

• Penthrane:

The simultaneous use of tetracycline and Penthrane® (methoxyflurane) has been linked to fatal renal toxicity.

The following are the side effects involving Doxycycline:

• Nausea
• Vomiting
• Diarrhea
• Upset stomach
• Loss of appetite
• Headache
• Dizziness
• Blurred vision
• Rash or skin sensitivity to sunlight
• Yeast infection (in women)
• Changes in the color of teeth (in children under 8 years old)
• Increased pressure within the skull (in rare cases).

Pregnancy:

Pregnancy Category D:

There is a lack of adequate and well-controlled studies on the use of doxycycline in pregnant women. The majority of reported cases of doxycycline use during human pregnancy involve short-term exposure during the first trimester. There is insufficient human data available to fully evaluate the effects of long-term therapy with doxycycline during pregnancy, particularly for the treatment of anthrax exposure. However, an expert review by TERIS, the Teratogen Information System, found that while the quantity and quality of data is limited to fair, therapeutic doses of doxycycline during pregnancy are unlikely to pose a significant teratogenic risk. Nonetheless, it cannot be conclusively stated that there is no risk.

A case-control study involving 18,515 mothers of infants with congenital anomalies and 32,804 mothers of the infants without congenital anomalies revealed a weak but marginally significant association between the use of doxycycline during pregnancy and total malformations. However, this association was not observed when the analysis was limited to maternal treatment during the period of organogenesis (i.e., the second and third months of gestation), except for a marginal relationship with neural tube defect based on only the two exposed cases.

Furthermore, a small prospective study of 81 pregnancies described 43 pregnant women who were treated with doxycycline for 10 days during the early first trimester. All the mothers reported that their exposed infants were normal at 1 year of age.

Nursing Mothers

Tetracyclines, including doxycycline, can be excreted in human milk, but the degree of absorption by breastfed infants is unclear. Short-term usage of doxycycline by lactating women is not necessarily contraindicated, but the impact of prolonged exposure to the drug through breast milk is unknown. Due to the possibility of severe adverse reactions in nursing infants from the drug doxycycline, a decision should be made based on the significance of the drug to the mother, whether to discontinue nursing or to discontinue the drug.

Pediatric Use

Due to the potential impact of tetracycline-class drugs on tooth development and growth, the use of Doxycycline is not recommended for pediatric patients under the age of 8, except for inhalational anthrax (post-exposure), when alternative treatments are unlikely to be effective or are contraindicated.

Geriatric Use

Clinical trials conducted on Doxycycline did not involve an adequate number of individuals aged 65 and over, making it unclear whether they respond differently than younger subjects. However, based on other clinical experience, no significant differences in responses have been observed between elderly and younger patients. When prescribing Doxycycline for elderly patients, it is advisable to exercise caution and initiate treatment at a lower dosage to account for the higher likelihood of the decreased hepatic, renal, or cardiac function, and the potential for concomitant disease or other drug therapy.

Physicians should be knowledgeable as well as vigilant about the treatment and identification of over dosage of Doxycycline.

If an overdose of the medication occurs, it is recommended to discontinue the use of the drug, manage the symptoms, and provide supportive care. Dialysis is not effective in treating cases of over dosage as it does not alter the serum half-life of the drug.

Pharmacodynamics

The antimicrobial effects of doxycycline and other tetracyclines are primarily bacteriostatic in nature, achieved through the inhibition of protein synthesis. By suppressing bacterial growth or keeping them in the stationary phase of growth, tetracyclines exert their antimicrobial effects. They exhibit a broad spectrum of activity against both gram-positive and gram-negative microorganisms. However, cross-resistance to tetracyclines is common among these microorganisms.

In addition to its favorable intra-cellular penetration, doxycycline is highly lipophilic and can cross multiple membranes of target molecules. It exhibits bacteriostatic activity against a wide range of bacteria and has antiparasitic properties. In addition, doxycycline exhibits anti-inflammatory actions and has been studied for its effects on inflammatory skin conditions, such as bullous dermatoses and rosacea.

Pharmacokinetics

● Absorption

Doxycycline exhibits high bioavailability, ranging from 73-95%, and is almost completely absorbed following oral administration. After a 500 mg dose, the maximum concentration (Cmax) of 15.3 mg/L is reached in 4 hours, while a 200 mg dose results in peak serum levels of 2.6 mcg/mL after 2 hours, decreasing to 1.45 mcg/mL after 24 hours. While the rate of absorption and Cmax are lowered by a high-fat meal, this effect is not considered clinically significant.

● Volume of Distribution

There is limited information available on the volume of distribution of doxycycline.

● Protein Binding

Tetracyclines, including doxycycline, bind to plasma proteins to varying degrees. The extent of protein binding is not well established, but there is limited information available.

● Metabolism

There is limited information available on the metabolism of doxycycline.

● Route of Elimination

The liver concentrates tetracyclines, including doxycycline, in bile, which is then excreted in high concentrations and in a biologically active form in urine and feces. In individuals with thre creatinine clearance of about 75 mL/min, the kidney eliminates approximately 40% of doxycycline in 72 hours. However, this percentage may decrease to as low as 1-5% in individuals with a creatinine clearance below 10 mL/min.

• https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/050795s005lbl.pdf
• https://www.drugs.com/pro/doxycycline.html
• https://pdf.hres.ca/dpd_pm/00042598.PDF
• https://www.pfizermedicalinformation.com/en-us/vibramycin
• https://docs.boehringer-ingelheim.com/Prescribing Information/PIs/Ben Venue_Bedford Labs/55390-110-10 DCY 100MG/5539011010
• https://www.webmd.com/drugs/2/drug-8648-7073/doxycycline-hyclate-oral/doxycycline-oral/details