Cephalexin is a first-generation cephalosporin. It develops its action preferentially on Gram-positive bacteria and much less frequently on Gram-negative bacteria. It is a beta-lactam antibiotic, whose mechanism of action is the lysis of the bacterial wall. In the useful spectrum are considered: Streptococcus beta-hemolytic, Staphylococcus aureus including strains producing penicillinase, Staphylococcus intermedius, Escherichia coli, Proteus mirabilis, Klebsiella spp., Haemophilus influenzae and Moraxella catarrhalis. Cephalexin is a stable acid that can be administered orally with meals. It is quickly absorbed by the intestinal tract and reaches peak plasma concentration one hour after administration. Plasma levels can be determined up to 6 hours after ingestion. The drug is excreted 70% by glomerular filtration and tubular secretion without changes in the urine up to 12 hours after administration. The elimination half-life is one and a half hours.
How Does Cephalexin Work?
Cephalexin may be indicated to treat infections of the respiratory tract, genitourinary, skin and soft tissues, bones and joints: pharyngotonsillitis, otitis media, peritonitis, sinusitis, bronchitis and pneumonia. Urethritis, cystitis, pyelitis, adnexitis and prostatitis. Furunculosis, abscesses, surgical and traumatic wounds, prophylaxis for dental interventions. It can also be used as a treatment in patients allergic to penicillins.
The recommended dose depends on the infection to be treated and the age of the person:
- Cephalexin 250 mg, 500 mg or 1 g tablets
It is used to treat streptococcal pharyngitis, skin infections and simple cystitis in patients more than 15 years of age in a dose of 500 mg or 1 g, and can be administered every 12 hours for a period of 7 to 14 days.
For infections of the respiratory tract caused by S. pneumoniae and S. pyogenes, it is necessary to use a dose of Сephalexin 500 mg every 6 hours.
More serious infections or kind of caused by less susceptible microorganisms require higher doses. If there is a need for daily Сephalexin dosage above 4 g, the physician should consider the use of an injectable cephalosporin in appropriate doses.
Cephalexin Warnings and Precautions
Contraindicated in patients allergic to beta-lactam molecules. There is the possibility of cross-sensitivity to penicillins. It is also contraindicated in cases of ulcerative colitis, regional enteritis, severe kidney failure, and during pregnancy and lactation. The risk of kidney damage appears to be low with the use of cephalexin; however, as a precautionary measure, its concomitant application with nephrotoxic drugs, such as aminoglycoside antibiotics, should be avoided and its administration avoided or done with extreme care in patients with kidney damage. It can give false-positive reactions for glucose in urine in patients who are under treatment with this antibiotic. It causes an elevation of serum transaminases.
There are several individuals that resort to swallowing cephalexin by taking help from food items, soft drinks, or fruit juices. Medical experts point out that this is something that should be avoided. The chemical composition of the medicine has the potential to adversely react if taken in combination with something else. A safer and tried tested option would be to go for swallowing gel that will not end up reacting with cephalexin in any way. If you have a problem, you can bring it up with your doctor and ask to be prescribed a swallowing gel to help you.
The concomitant use of parenteral aminoglycosides or other nephrotoxic drugs (eg amphotericin B) cephalosporins used to be provocative. Possibly cephalosporins can cause preservative nephrotoxicity at the time used with these drugs, but this interaction only has been recognised with cephaloridine, which used to be no longer on the market. Despite this, caution is recommended when associating these drugs with cephalexin.
Medical studies have proven that cephalosporins can be synergistic or have preservative activity against specific bacteria at the time used with penicillin, aminoglycosides, or chloramphenicol. Nevertheless, certain clinicians don’t suggest the concomitant use of cephalosporins with bacteriostatic antibiotics (such as chloramphenicol) mainly in infections where the microorganism is proliferating rapidly.
Probenecid competitively blocks the tubular secretion of most cephalosporins, thereby increasing blood levels and plasma half-life.
Use with caution in patients receiving oral anticoagulants.
Cephalosporins can cause false-positive reactions in urine glucose tests when using cupric sulfate (Benedict’s solution). Tests using glucose oxidase are not affected by the use of the product.
How should this medicine be used?
Cephalexin originates as a tablet, capsule, and suspension (liquid) for oral administration. It happens to be typically taken with or without food every 6 – 12 hours for 7 – 14 days, based on the situation being treated. Have cephalexin at around the same time every day. Follow the instructions on your prescription label cautiously, and ask your medical consultant or the pharmacist to clarify any parts that you do not understand. Consume cephalexin precisely as prescribed. Do not consume additional or less of the medicine, or have it more frequently than the prescription of your doctor.
Shake the liquid well before each use to mix the medicine evenly.
You should start to feel better during the first few days of treatment with cephalexin. If your symptoms don’t improve or get worse, call your doctor.
Keep taking cephalexin until the prescription is finished, even if you feel better. In the event that you stop having cephalexin too miss or soon some doses, the infection might not be fully treated and the bacteria might become unaffected to the antibiotics.
What are the side effects that this medicine could cause?
Cephalexin may cause side effects. Inform your doctor if such symptoms happen to be severe or do not be off:
- Stomach ache
- Genital or rectal itching
- Severe agitation
- Articulations pain
Certain Side Effects might Be Serious. If you experience any of the following symptoms, call your doctor immediately or seek emergency medical treatment:
- Bloody or liquid stools, stomach cramps, or fever at the time of treatment or equal to two or additional months post stopping treatment
- Swelling of the face, throat, tongue, lips, and eyes
- Difficulty breathing or swallowing
- Sore throat, return of fever, chills, or other symptoms of infection
- Hallucinations (seeing things or hearing voices that don’t exist)
Cephalexin and alcohol
Alcohol does not reduce the effectiveness of cephalexin. The information in the cephalexin package insert also does not indicate that alcohol interacts with this medicine.
However, some of the more common side effects of this drug are similar to a few of the additional annoying effects of alcohol, such as drowsiness, dizziness, and nausea. Having Сephalexin and alcohol together might increase these effects. In the event that happens, it may be best to stop drinking alcohol until the treatment is finished.