Tetracyclines adverse effects

Tetracyclines are used as alternative dnigs in a variety of circumstances when the patient is unable to take the dnig of choice, eg, in patients allergic to penicillin (88,89). Tetracyclines are widely known to cause staining of teeth (and are therefore contra-indicated in children developing permanent teeth), photosensitivity, and, in the case of minocycline, vestibular toxicity. Details of these adverse effects and others associated with administration of tetracyclines have been comprehensively reviewed (96—101). 

Common adverse effects of calcium salts include constipation, bloating, cramps, and flatulence. Changing to a different salt form may alleviate symptoms for some patients. Calcium salts may reduce the absorption of levothyroxine, iron and some antibiotics, such as tetracycline and fluoroquinolones. 

Adverse effects with the tetracyclines include gastrointestinal upset drug interactions with dairy products, antacids, and iron and phototoxicity. Minocycline can also cause vestibular complications (headache and dizziness) and skin discoloration that is not typical with tetracycline and doxycycline.16... 

The answer is c. (Hardman, pp 1134-1135.) Hematologic toxicity is by far the most important adverse effect of chloramphenicol The toxicity consists of two types (1) bone marrow depression (common) and (2) aplastic anemia (rare) Chloramphenicol can produce a potentially fatal toxic reaction, the gray baby syndrome, caused by diminished ability of neonates to conjugate chloramphenicol with resultant high serum concentrations. Tetracyclines produce staining of the teeth and phototoxicity... 

Tetracyclines inhibit P. acnes, reduce the amount of keratin in sebaceous follicles, and have antiinflammatory properties (inhibiting chemotaxis, phagocytosis, complement activation, and cell-mediated immunity). Drawbacks to tetracyclines include hepatotoxicity and predisposition to infections (e.g., vaginal candidiasis). Other adverse effects include GI disturbances, photosensitivity, tooth discoloration in children, and inhibition of skeletal growth in the developing fetus. Tetracyclines must not be combined with systemic retinoids because of an increased risk of intracranial hypertension. / Tetracycline is the least expensive agent in this class and is often... 

Doxycycline is commonly used for moderate to severe acne vulgaris. It is more effective and produces less resistance than tetracycline. The initial dose is 100 or 200 mg daily, followed by 50 mg daily as a maintenance dose after improvement is seen. Doxycycline maybe given with food, but it is more effective when taken 30 minutes before meals. / Minocycline is also commonly used for moderate to severe acne vulgaris. It is more effective than tetracycline. It is dosed similar to doxycycline (100 mg/day or 50 mg twice daily) and on an indefinite basis in selected patients. Minocycline has the most reported adverse effects of the tetracyclines, some of which may be serious. 

There are a number of factors that limit the effectiveness of regimens designed to eradicate H. pylori. The first, antibiotic resistance, is seen with metronidazole and clarithromycin but has not been reported with bismuth, amoxicillin, or tetracycline. Second, mild adverse effects (eg, diarrhea, metallic taste, black stools) do occur in approximately 30% to 50% of patients. Therefore, shorter treatment periods in this group of patients may be better tolerated. 

Tetracyciine ciass antibiotics Glycylcycline class antibiotics are structurally similar to tetracycline class antibiotics and may have similar adverse effects. Such effects may include photosensitivity, pseudotumor cerebri, pancreatitis, and antianabolic action (which has led to increased serum urea nitrogen [BUN], azotemia, acidosis, and hypophosphatemia). 

Adverse effects consist mainly of gastrointestinal intolerance such as nausea, epigastric pain and diarrhea and, especially in the elderly constipation with continued therapy. All ferrous salts may cause a black coloration of the faeces. Children are particularly susceptible to potentially lethal iron intoxications. Oral iron preparations should not be administered concurrently with tetracyclines as mutual interference with absorption will occur. 

Hypersensitivity reactions (drug fever, skin rashes) to tetracyclines are uncommon. Most adverse effects are due to direct toxicity of the drug or to alteration of microbial flora. 

Malarone is generally well tolerated. Adverse effects include abdominal pain, nausea, vomiting, diarrhea, headache, and rash, and these are more common with the higher dosage required for treatment. Reversible elevations in liver enzymes have been reported. The safety of atovaquone in pregnancy is unknown. Plasma concentrations of atovaquone are decreased about 50% by co-administration of tetracycline or rifampin. 

Adverse effects associated with lithium therapy include tremulousness, mental obtundation, cardiotoxicity, thyroid dysfunction, and leukocytosis (see Chapter 29 Antipsychotic Agents Lithium). Demeclocycline should be avoided in patients with liver disease (see Chapter 44 Chloramphenicol, Tetracyclines, Macrolides, Clindamycin, Streptogramins) and in children younger than 12 years. 

Pregnancy All antibiotics cross the placenta. Adverse effects to the fetus are rare, except for tooth dysplasia and inhibition of bone growth encountered with the tetracyclines. However, some anthelmintics are embryotoxic and teratogenic (p. 359). Aminoglycosides should be avoided in pregnancy because of their ototoxic effect in the fetus. 

Some adverse effects of tetracycline. synthesis by the mechanism determined for streptomycin [strep toe... 

Tetracyclines are recommended as first-line treatment. When tetracyclines are not tolerated or contraindicated, erythromycin is an alternative. However erythromycin has problems with resistance and gastrointestinal adverse effects. If compliance is a problem, either doxycycline or lymecycline may be prescribed (can be taken once daily with food). Minocycline is second-line treatment (e.g. if oral antibiotic has failed). 

Table 2 Adverse effects in a comparison of artesunate plus tetracycline versus quinine...

Compared with tetracycline, azithromycin had a favorable short-term effect on childhood morbidity in a mass trial for trachoma in rural Gambian villages, and adverse effects were limited (13). 

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