Phenoxymethylpenicillin
Encyclopedia
Phenoxymethylpenicillin, commonly known as penicillin V, is a penicillin
antibiotic that is orally active. It is less active than benzylpenicillin
(penicillin G) against Gram-negative bacteria. Phenoxymethylpenicillin is more acid-stable than benzylpenicillin, which allows it to be given orally. It exerts a bactericidal action against penicillin-sensitive microorganisms during the stage of active multiplication. It acts by inhibiting
the biosynthesis
of cell-wall peptidoglycan
. It is not active against beta-lactamase
-producing bacteria, which include many strains of staphylococci
.
Phenoxymethylpenicillin has a range of antimicrobial activity against Gram-positive bacteria that is similar to that of benzylpenicillin and a similar mode of action, but it is substantially less active than benzylpenicillin against Gram-negative bacteria.
Phenoxymethylpenicillin is usually used only for the treatment of mild to moderate infections, and not for severe or deep-seated infections since absorption
can be unpredictable. Except for the treatment or prevention of infection with Streptococcus pyogenes
(which is uniformly sensitive to penicillin), therapy should be guided by bacteriological studies (including sensitivity tests) and by clinical response. Patients treated initially with parenteral
benzylpenicillin may continue oral treatment with phenoxymethylpenicillin once a satisfactory clinical response has been obtained..
For prophylaxis against rheumatic fever
, phenoxymethylpenicillin given orally twice a day is used as an alternative to injections of benzathine penicillin
given every two weeks.
Penicillin V is sometimes used in the treatment of odontogenic infections.
, vomiting, epigastric distress, diarrhea
, and black hairy tongue. A previous hypersensitivity reaction
to any penicillin
is a contraindication
.
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
antibiotic that is orally active. It is less active than benzylpenicillin
Benzylpenicillin
Benzylpenicillin, commonly known as penicillin G, is the gold standard type of penicillin. 'G' in the name 'Penicillin G' refers to 'Gold Standard'. Penicillin G is typically given by a parenteral route of administration because it is unstable in the hydrochloric acid of the stomach...
(penicillin G) against Gram-negative bacteria. Phenoxymethylpenicillin is more acid-stable than benzylpenicillin, which allows it to be given orally. It exerts a bactericidal action against penicillin-sensitive microorganisms during the stage of active multiplication. It acts by inhibiting
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
the biosynthesis
Protein biosynthesis
Protein biosynthesis is the process in which cells build or manufacture proteins. The term is sometimes used to refer only to protein translation but more often it refers to a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA, which is then...
of cell-wall peptidoglycan
Peptidoglycan
Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria , forming the cell wall. The sugar component consists of alternating residues of β- linked N-acetylglucosamine and N-acetylmuramic acid...
. It is not active against beta-lactamase
Beta-lactamase
Beta-lactamases are enzymes produced by some bacteria and are responsible for their resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems . These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam...
-producing bacteria, which include many strains of staphylococci
Staphylococcus
Staphylococcus is a genus of Gram-positive bacteria. Under the microscope they appear round , and form in grape-like clusters....
.
Phenoxymethylpenicillin has a range of antimicrobial activity against Gram-positive bacteria that is similar to that of benzylpenicillin and a similar mode of action, but it is substantially less active than benzylpenicillin against Gram-negative bacteria.
Phenoxymethylpenicillin is usually used only for the treatment of mild to moderate infections, and not for severe or deep-seated infections since absorption
Absorption (Pharmacokinetics)
In pharmacology , absorption is the movement of a drug into the bloodstream.Absorption involves several phases...
can be unpredictable. Except for the treatment or prevention of infection with Streptococcus pyogenes
Streptococcus pyogenes
Streptococcus pyogenes is a spherical, Gram-positive bacterium that is the cause of group A streptococcal infections. S. pyogenes displays streptococcal group A antigen on its cell wall. S...
(which is uniformly sensitive to penicillin), therapy should be guided by bacteriological studies (including sensitivity tests) and by clinical response. Patients treated initially with parenteral
Parenteral
Parenteral is a route of administration that involves piercing the skin or mucous membrane. Parenteral nutrition refers to providing nutrition via the veins.-Etymology:...
benzylpenicillin may continue oral treatment with phenoxymethylpenicillin once a satisfactory clinical response has been obtained..
For prophylaxis against rheumatic fever
Rheumatic fever
Rheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as strep throat or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after...
, phenoxymethylpenicillin given orally twice a day is used as an alternative to injections of benzathine penicillin
Benzathine benzylpenicillin
Benzathine benzylpenicillin is a form of penicillin also known as benzathine penicillin. It is slowly absorbed into the circulation, after intramuscular injection, and hydrolysed to benzylpenicillin in vivo...
given every two weeks.
Medical uses
Specific indications for phenoxymethylpenicillin include:- Infections caused by Streptococcus pyogenesStreptococcus pyogenesStreptococcus pyogenes is a spherical, Gram-positive bacterium that is the cause of group A streptococcal infections. S. pyogenes displays streptococcal group A antigen on its cell wall. S...
- TonsillitisTonsillitisTonsillitis is an inflammation of the tonsils most commonly caused by viral or bacterial infection. Symptoms of tonsillitis include sore throat and fever. While no treatment has been found to shorten the duration of viral tonsillitis, bacterial causes are treatable with antibiotics...
- PharyngitisPharyngitisPharyngitis is an inflammation of the throat or pharynx. In most cases it is quite painful, and is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic....
- SkinSkin-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
infections
- Tonsillitis
- AnthraxAnthraxAnthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals...
(mild uncomplicated infections) - Lyme diseaseLyme diseaseLyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...
(early stage in pregnant women or young children) - PharyngitisPharyngitisPharyngitis is an inflammation of the throat or pharynx. In most cases it is quite painful, and is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic....
or tonsillitisTonsillitisTonsillitis is an inflammation of the tonsils most commonly caused by viral or bacterial infection. Symptoms of tonsillitis include sore throat and fever. While no treatment has been found to shorten the duration of viral tonsillitis, bacterial causes are treatable with antibiotics... - Rheumatic feverRheumatic feverRheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as strep throat or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after...
(primary and secondary prophylaxis) - StreptococcalStreptococcusStreptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...
skin infections - Spleen disorders (pneumococcal infection prophylaxis)
- Moderate-to-severe gingivitisGingivitisGingivitis is a term used to describe non-destructive periodontal disease. The most common form of gingivitis is in response to bacterial biofilms adherent to tooth surfaces, termed plaque-induced gingivitis, and is the most common form of periodontal disease...
(with metronidazoleMetronidazoleMetronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Metronidazole is an antibiotic, amebicide, and antiprotozoal....
) - Avulsion injuries of teeth (as an alternative to tetracycline)
Penicillin V is sometimes used in the treatment of odontogenic infections.
Adverse Effects and Precautions
Phenoxymethylpenicillin is usually well tolerated but may occasionally cause transient nauseaNausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, vomiting, epigastric distress, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, and black hairy tongue. A previous hypersensitivity reaction
Hypersensitivity
Hypersensitivity refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification...
to any penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
is a contraindication
Contraindication
In medicine, a contraindication is a condition or factor that serves as a reason to withhold a certain medical treatment.Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action...
.