Tetracyclines photosensitivity

Topical tetracyclines are sometimes used to treat acne and minor superficial pyogenic infections of the skin. Patients hypersensitive to one member of this class of antibiotics may also be hypersensitive to other tetracyclines. Photosensitization may occur. 

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). 

Doxycycline (Vibramycin) is an antibiotic belonging to die tetracycline group of antibiotics. The adverse reactions associated with this drug are discussed in Chapter 9 and include photosensitivity, anorexia, nausea, and vomiting. 

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... 

UV irradiation (335 nm) at pH 7.3 showed that some tetracyclines produced significant concentrations of the superoxide anion radical. Demeclocycline (122), oxytetracycline (123) and chlortetracycline (124) were the most active in this. These are all potent photosensitizers and probably give the observed exaggerated sunburn as a result of superoxide production in the skin [90]. Other photochemical experiments demonstrated the production of singlet oxygen. Yields obtained by luminescence measurements in alkaline ethanol were in the order (122) > (120) > (124) > (121) > (125). Chlortetracycline... 

Antibiotics Cephalosporins Chloramphenicol Neomycin Sulfathiazole Spiramycin Quinolones Tetracyclines Hypersensitivity Anaphylaxis, urticaria, rash, granulocytopenia Rash, dermatitis, urticaria Dermal exposure-rash, dermatitis Rash, dermatitis, urticaria Rash, dermatitis, urticaria Photosensitivity Photosensitivity, anaphylaxis, asthma, dermatitis... 

Several drug classes, including tetracycline, sulfonamide, and quinolone antibiotics, as well as chlorothiazide, chlorpromazine, and amiodarone hydrochloride, have been shown to be photoantigens. Photosensitivity may persist even after withdrawal of the drug, as has been observed with the antiarrhythmic drug amiodarone hydrochloride, since it is lipophilic and can be stored for extended periods in the body fat (Unkovic et al., 1984). In addition, it is quite common for cross-reactions to occur between structurally related drugs of the same class. 

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

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). 

Sulfacetamide Prednisolone (Blephamide, Others) [AntibiotiC/ Anti-inflammatory] Uses Steroid-responsive inflammatory ocular conditions w/ Infxn or a risk of Infxn Action Antibiotic anti-inflammatory Dose Adults Feds >2 y. Apply oint lower conjunctival sac daily-qid soln 1-3 gtt 2-3 h while awake Caution [C, /-] Sulfonamide sensitivity age <2 mo Disp Oint, susp SE Irritation, burning, blurred vision, brow ache, Stevens-Johnson synd, photosens Interactions T Effects W/ tetracyclines EMS T Risk of photosensitivity Rxns OD Unlikely to cause life-threatening Sxs... 

A patient is admitted with what looks like extensive first degree burns over nearly the whole body. These have occurred since the patient had been on holiday. You diagnose sunburn and get into a debate with the patient who claims to have been very careful and has never had such a problem before. What you have missed is that the patient had an ear infection on the flight, which caused pain, went to a local doctor and was given tetracycline-a well known cause of photosensitivity. 

Demeclocycline has a spectrum of activity comparable to tetracycline but it may cause nephrogenic diabetes insipidus. It is also associated with a high incidence of photosensitivity. 

Tetracycline Prevents bacterial protein synthesis by binding to the 30S ribosomal subunit Bacteriostatic activity against susceptible bacteria Infections caused by mycoplasma, chlamydiae, rickettsiae, some spirochetes malaria H pylori acne Oral mixed clearance (half-life 8 h) dosed every 6 h divalent cations impair oral absorption Toxicity Gastrointestinal upset, hepatotoxicity, photosensitivity, deposition in bone and teeth... 

Due to their extremely polar character, tetracyclines bind with proteins to form conjugates that are difficult to extract from biological matrices. Use of dilute mineral acids is of great help in dissociating tetracyclines from proteins, but once in aqueous solution, their exfraction into volatile organic solvents for further concentration and cleanup is hampered by the unfavorable partition coefficients. Most of these antibiotics are photosensitive compounds, whereas all of them show poor stability under strong acidic and alkaline conditions with reversible formation of the 4-epi-tetracyclines in weakly acidic conditions (pH 3), and anhydro-tetracyclines in strong acidic conditions (below pH 2). 

Doxycydine (Adoxa, Periostal-, Oracea, Vibramycin, Vibra-Tabs) [Anribiotic/Tetracycline] Uses Broad-spectrum antibiotic acne vulgaris, uncomplicated GC, Chlamydia sp, PID, Lyme Dz, skin Infxns, anthrax, malaria prophylaxis Action Tetracycline bacteriostatic X- protein synth Dose Adults. 100 mg PO ql2h on 1st d, then 100 mg PO daily bid or 100 mg IV ql2h acne daily dosing, Chlamydia 7d, Lyme Dz 14—21 d, PID 14 d Peds >8 y 5 mg/kg/24 h PO, to a max of 200 mg/d - daily-bid Caution [D, +] Hepatic impair Contra Children <8 y, severe hepatic dysfxn Disp Tabs, caps, syrup, susp, inj SE D, GI disturbance, photosens Interactions T Effects OF digoxin, warfarin 1 effects W/ antacids, Fe, barbiturates, carbamazepine, phenytoins, food 4-effects OF penicillins EMS Monitor for signs of electrolyte disturbances and hypovolemia d/t D monitor for S/Sxs of super Infxn T risk of photosensitivity Rxns antibiotic of choice for the Tx and prophylaxis of anthrax exposure expired tetracyclines have been known to cause nephrotox OD May cause adverse GI effects symptomatic and supportive... 

Gastrointestinal distress (nausea, vomiting, diarrhea) may be a problem with tetracycline use. Hypersensitivity reactions (such as rashes) may also occur, as well as an increase in skin sensitivity to ultraviolet light (photosensitivity).16 Tetracyclines form chemical complexes with calcium that may impair the growth and development of calcified tissues such as bone and teeth, especially in children.69 Tetracyclines also cause discoloration of teeth in children and pregnant women, apparently because of the tetracycline-calcium interaction.69 As mentioned previously, development of tetracycline-resistant strains and resulting superinfections may be a serious problem during tetracycline therapy. 

Before the introduction of specific vasopressin receptor antagonists, pharmacological treatments for hyponatremia centered on the use of loop diuretics and nonspecific inhibitors of vasopressin signaling, such as lithium carbonate and demeclocycline.11 The utility of such therapies has been limited by a range of sideeffects. Loop diuretic use can result in electrolyte imbalances and suffers from poor response predictability.11 Lithium carbonate suffers from a low therapeutic index and a risk of renal damage as well as limited effectiveness in many patients. Lithium carbonate has therefore been nearly completely supplanted by demeclocycline, a tetracycline antibiotic, in the treatment of chronic hyponatremia.12 Demeclocycline use is itself limited by its nephrotoxicity (particularly in cirrhotic patients), ability to cause reversible uremia, and ability to induce photosensitivity.1,11... 

Correct choice = B. At high concentrations, tetracycline enters mammalian cells by diffusion and interacts with mitochondrial ribosomes, blocking access of the amino acyl-tRNA to the mRNA-ribosome complex at the acceptor site. Severe photosensitive dermatitis occurs when the patient receiving tetracycline is exposed to sun or ultraviolet rays. 

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