Actions of Doxycycline in details
Pharmacology: Pharmacodynamics: Doxycycline is primarily bacteriostatic and is thought to exert its antimicrobial effect by the inhibition of protein synthesis.
Pharmacokinetics: 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. Studies reported to date indicate that the absorption of Doxycycline, unlike certain other tetracyclines, is not notably influenced by the ingestion of food or milk.
In Doxycycline carrageenate tablets, Doxycycline is bound to the sulfated polysaccharide carrageenan. In dissolution tests, the release of Doxycycline from the carrageenate complex is not reduced with increased pH. In addition, it has been demonstrated in volunteers that pre-treatment with the gastric proton-pump inhibitor omeprazole does not influence the bioavailability of Doxycycline when it is administered as Doxycycline carrageenate.
Following a 200-mg dose, normal adult volunteers averaged peak serum levels of 2.6 mcg/mL of Doxycycline at 2 hrs, decreasing to 1.45 mcg/mL at 24 hrs. Excretion of Doxycycline by the kidney is about 40%/72 hrs in individuals with normal renal function (creatinine clearance about 75 mL/min). This percentage excretion may fall to a range as low as 1-5%/72 hrs in individuals with severe renal insufficiency (creatinine clearance <10 mL/min). Studies have shown no significant difference in serum half-life of Doxycycline (range: 18-22 hrs) in individuals with normal and severely impaired renal function.
Toxicology: Preclinical Safety Data: Long-term studies in animals to evaluate carcinogenic potential of Doxycycline have not been conducted. However, there has been evidence of oncogenic activity in rats in studies with the related antibiotics, oxytetracycline (adrenal and pituitary tumors) and minocycline (thyroid tumors).
Likewise, although mutagenicity studies of Doxycycline have not been conducted, positive results in in vitro mammalian cell assays have been reported for related antibiotics (tetracycline, oxytetracycline).
Doxycycline administered orally at dosage levels as high as 250 mg/kg/day had no apparent effect on the fertility of female rats. Effect on male fertility has not been studied.
Microbiology: Doxycycline is active against a wide range of gram-positive and gram-negative microorganisms including:
Gram-Negative Bacteria: Acinetobacter sp (formerly Mima and Herellea sp), Bacteroides sp, Bartonella bacilliformis, Brucella sp, Calymmatobacterium granulomatis, Campylobacter fetus, Enterobacter aerogenes, Escherichia coli, Francisella tularensis (formerly Pasteurella tularensis), Haemophilus ducreyi, Haemophilus influenzae, Klebsiella sp, Neisseria gonorrhoeae, Shigella sp, Vibrio cholerae (formerly Vibrio comma), Yersinia pestis (formerly Pasteurella pestis).
Gram-Positive Bacteria: Enterococcus groups (S. faecalis and S. faecium), Streptococcus pneumoniae, Streptococcus pyogenes.
Other Microorganisms: Actinomyces sp, Bacillus anthracis, Balantidium coli, Borrelia burgdorferi, Borrelia duttonii, Borrelia recurrentis, Chlamydia psittaci, Chlamydia trachomatis, Clostridium sp, Entamoeba sp, Fusobacterium sp, Leptotrichia buccalis (formerly Fusobacterium fusiforme), Leptospira sp, Listeria monocytogenes, Mycoplasma pneumoniae, Plasmodium falciparum (asexual erythrocytic forms only), Propionibacterium acnes, Rickettsiae, Treponema pallidum, Treponema pertenue, Ureaplasma urealyticum.
How should I take Doxycycline?
Take Doxycycline exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Take Doxycycline with a full glass of water (8 ounces) while sitting or standing. To prevent irritation to your throat, do not lay down right after taking a capsule.
The usual dose of Doxycycline is one capsule in the morning on an empty stomach. You should take at least one hour before or two hours after a meal.
Do not take Doxycycline with or right after taking antacids or products that contain calcium, aluminum, magnesium, or iron. It may not work as well.
Do not crush, break, or open a Doxycycline delayed-release capsule. Swallow the capsule whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time. Take this medicine for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Do not give this medicine to another person, even if they have the same condition you have.
If you need to have any type of surgery, tell the surgeon ahead of time that you are taking Doxycycline. You may need to stop using the medicine for a short time.
Throw away any unused Doxycycline when it expires or when it is no longer needed. Do not take this medicine after the expiration date printed on the label. Using expired Doxycycline can cause damage to your kidneys.
Store at room temperature away from moisture and heat.
Doxycycline administration
Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Take Doxycycline with a full glass of water. Drink plenty of liquids while you are taking Doxycycline.
Different brands of Doxycycline may have different instructions about taking them with or without food.
Most brands of doxycyline may be taken with food or milk if the medicine upsets your stomach.
Take Doxycycline or Periostat on an empty stomach, at least 1 hour before or 2 hours after a meal.
You may open a Doxycycline capsule or break up a Doxycycline tablet and sprinkle the medicine into a spoonful of applesauce to make swallowing easier. Swallow right away without chewing. Do not save the mixture for later use. Drink a full glass (8 ounces) of cool water right away.
Do not crush, break, or open a delayed-release capsule. Swallow the pill whole. Breaking or opening the pill may cause too much of the drug to be released at one time. The enteric coated pill has a special coating to protect your stomach. Breaking the pill will damage this coating.
Measure liquid medicine with a special dose measuring spoon or medicine cup, not with a regular table spoon. If you do not have a dose measuring device, ask your pharmacist for one.
Take this medication for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Doxycycline will not treat a viral infection such as the common cold or flu.
If you need surgery, tell the surgeon ahead of time that you are using Doxycycline. You may need to stop using the medicine for a short time.
Store at room temperature away from moisture and heat.
Throw away any unused medicine after the expiration date on the label has passed. Using expired Doxycycline can cause damage to your kidneys.
Doxycycline pharmacology
Mechanism of Action
The mechanism of action of Doxycycline in the treatment of inflammatory lesions of rosacea is unknown.
Pharmacokinetics
Doxycycline capsules are not bioequivalent to other Doxycycline products. The pharmacokinetics of Doxycycline following oral administration of
Doxycycline was investigated in 2 volunteer studies involving 61 adults. Pharmacokinetic parameters for Doxycycline following single oral doses and at steady-state in healthy subjects are presented in Table 2.
Absorption: In a single-dose food-effect study involving administration of Doxycycline to healthy volunteers, concomitant administration with a 1000 calorie, high-fat, high-protein meal that included dairy products, resulted in a decrease in the rate and extent of absorption (Cmax and AUC) by about 45% and 22%, respectively, compared to dosing under fasted conditions. This decrease in systemic exposure can be clinically significant, and therefore if Doxycycline is taken close to meal times, it is recommended that it be taken at least one hour prior to or two hours after meals.
Distribution: Doxycycline is greater than 90% bound to plasma proteins.
Metabolism: Major metabolites of Doxycycline have not been identified. However, enzyme inducers such as barbiturates, carbamazepine, and phenytoin decrease the half-life of Doxycycline.
Excretion: Doxycycline is excreted in the urine and feces as unchanged drug. It is reported that between 29% and 55.4% of an administered dose can be accounted for in the urine by 72 hours. Terminal half-life averaged 21.2 hours in subjects receiving a single dose of Doxycycline.
Special Populations
Geriatric: Doxycycline pharmacokinetics have not been evaluated in geriatric patients.
Pediatric: Doxycycline pharmacokinetics have not been evaluated in pediatric patients.
Gender: The pharmacokinetics of Doxycycline were compared in 16 male and 14 female subjects under fed and fasted conditions. While female subjects had a higher Cmax and AUC than male subjects, these differences were thought to be due to differences in body weight/lean body mass.
Race: Differences in Doxycycline pharmacokinetics among racial groups have not been evaluated.
Renal Insufficiency: Studies have shown no significant difference in serum half-life of Doxycycline in patients with normal and severely impaired renal function. Hemodialysis does not alter the serum half-life of Doxycycline.
Hepatic Insufficiency: Doxycycline pharmacokinetics have not been evaluated in patients with hepatic insufficiency.
Gastric Insufficiency: In a study in healthy volunteers (N=24) the bioavailability of Doxycycline is reported to be reduced at high pH. This reduced bioavailability may be clinically significant in patients with gastrectomy, gastric bypass surgery or who are otherwise deemed achlorhydric.
Drug Interactions:.
Microbiology
Doxycycline is a member of the tetracycline-class of drugs. The plasma concentrations of Doxycycline achieved with Doxycycline during administration are less than the concentration required to treat bacterial diseases. Doxycycline should not be used for treating bacterial infections, providing antibacterial prophylaxis, or reducing the numbers or eliminating microorganisms associated with any bacterial disease. In vivo microbiological studies utilizing a similar drug exposure for up to 18 months demonstrated no detectable long term effects on bacterial flora of the oral cavity, skin, intestinal tract and vagina.
References
- DailyMed. "DOXYCYCLINE: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- NCIt. "Doxycycline Hyclate: NCI Thesaurus (NCIt) provides reference terminology for many systems. It covers vocabulary for clinical care, translational and basic research, and public information and administrative activities.". https://ncit.nci.nih.gov/ncitbrowser... (accessed September 17, 2018).
- EPA DSStox. "Doxycycline: DSSTox provides a high quality public chemistry resource for supporting improved predictive toxicology.". https://comptox.epa.gov/dashboard/ds... (accessed September 17, 2018).
Reviews
The results of a survey conducted on ndrugs.com for Doxycycline are given in detail below. The results of the survey conducted are based on the impressions and views of the website users and consumers taking Doxycycline. We implore you to kindly base your medical condition or therapeutic choices on the result or test conducted by a physician or licensed medical practitioners.User reports
4 consumers reported administration
When best can I take Doxycycline, on an empty stomach, before or after food?ndrugs.com website users have also released a report stating that Doxycycline should be taken Before food. In any case, this may not be the right description on how you ought to take this Doxycycline. Kindly visit your doctor for more medical advice in this regard. Click here to see other users view on when best the Doxycycline can be taken.
| Users | % | ||
|---|---|---|---|
| Before food | 1 | 25.0% | |
| With a meal | 1 | 25.0% | |
| Empty stomach | 1 | 25.0% | |
| After food | 1 | 25.0% | |
Consumer reviews
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Information checked by Dr. Sachin Kumar, MD Pharmacology
