Penicillin V, also called Phenoxymethylpenicillin, is commonly used in tablets form, as well as oral liquid or oral suspension. Penicillin v is white crystal or crystalline powder; odorless or slightly odorless, slightly bitter. It is not destroyed after oral administration with the absorption rate is 60%, and its absorption is not affected by food in the stomach.
The peak blood concentration is reached 0.5 to 1 hour after oral administration. The binding rate to plasma protein in plasma is high. 56% of it is inactivated by liver metabolism, 20%-40% is excreted by kidney, t1/2 is 1 hour.
The antibacterial spectrum of penicillin v is the same as that of penicillin g. It mainly acts on bacteria during the breeding period and has an antibacterial effect. It has obvious antibacterial effect on sensitive streptococcus, pneumococcus and staphylococcus and other gram-positive bacteria. Penicillin v is not only well absorbed by oral administration, but the speed of destruction by penicillinase is slower than penicillin g, so it has a stronger effect on drug-resistant Staphylococcus aureus than the latter. Penicillin v can be used for tonsillitis, pharyngitis, scarlet fever, pneumonia, detracheitis, otitis media caused by sensitive bacteria, and various abscesses.
Penicillin v is easily soluble in water, and almost insoluble in chloroform, ether or liquid paraffin. Take an appropriate amount of penicillin v, accurately weigh it, add freshly boiled water and cool it to room temperature to make a solution containing about 10mg per 1ml, measured according to law (Appendix VIE), the specific rotation is +215° to +230°.
Penicillin v is stable to acid and well absorbed by oral administration. The serum concentration is about 2 to 3 times that of the same oral penicillin dose. Its antibacterial spectrum is exactly the same as penicillin. It has antibacterial activity against most gram-positive bacteria, gram-negative cocci, individual gram-negative bacilli (such as Haemophilus), spirochetes and actinomycetes, but most staphylococcal strains (>90%) include Staphylococcus aureus and coagulase-negative staphylococci can produce beta lactamase to hydrolyze the product and inactivate it.
The activity of penicillin v against most sensitive strains is 2 to 5 times weaker than penicillin. It has no antibacterial effect on penicillinase producing strains. The mechanism of action of penicillin v is to inhibit the synthesis of bacterial cell wall, so that the bacteria quickly rupture and dissolve.
Oral absorption is fast and complete. The blood concentration can reach the peak after one hour, and 30% of penicillin v is excreted in the urine after 24 hours. Penicillin v penetrates into the chest cavity and abdominal cavity with a high concentration, but it is difficult to penetrate the blood-brain barrier.
Penicillin v is acid-resistant, and food can reduce its absorption. The protein binding rate is about 80%. 20% to 35% of the dose is excreted in the urine in its original form. The blood elimination half-life (t1/2β) of penicillin v is about 1 hour.
Penicillin v is suitable for mild and moderate infections caused by penicillin-sensitive strains, including tonsillitis, pharyngitis, scarlet fever, erysipelas caused by streptococcus; bronchitis, pneumonia, otitis media, sinusitis and sensitive grapes caused by pneumococcus Skin and soft tissue infections caused by cocci.
Penicillin v can also be used for spirochetes infection and as a preventive medication for rheumatic fever recurrence and infective endocarditis.
Penicillin v is acid-stable and has good oral absorption. The serum concentration is about 2 to 3 times that of the same dose of penicillin. Its antibacterial spectrum is exactly the same as penicillin. It is effective against infections introduced by gram-positive bacteria and drug-resistant Staphylococcus aureus. It is clinically used to treat tonsillitis, pharyngitis, otitis media, pneumonia, bronchitis, scarlet fever, etc. caused by Staphylococcus, hemolytic streptococcus and pneumococcus and cellulitis, erysipelas and other soft tissue infections.
A. Scarlet fever
Scarlet fever is an acute respiratory infection caused by group A beta hemolytic streptococcus, and can also cause tonsillitis, erysipelas, rheumatic fever, endocarditis and local infections. It is clinically characterized by fever, angina, diffuse scarlet skin rash, and skin desquamation after the rash. Some people may have allergic heart and kidney complications after illness. This disease occurs all year round, especially in winter and spring. It is more common in children, especially 2-8 years old. Western medicine treatment plan provides antibiotic therapy, penicillin V, penicillin G, or erythromycin if you are allergic to penicillin drugs.
Erysipelas is an infection involving the lymphatic vessels of the superficial dermis. The main pathogen is group A beta hemolytic streptococcus. The predisposing factors are surgical wounds or fissures in the nostrils, external ear canal, anus, penis and toes.
Any inflammation of the skin, especially inflammation with cracks or ulcers, provides a way for pathogenic bacteria to invade. Mild abrasions or scratches, injuries other than the head, unclean umbilical cord ligation, vaccinations, and chronic calf ulcers can cause this disease. Pathogenic bacteria can lurch in the lymphatic vessels and relapse.
Tonsillitis can be divided into acute tonsillitis and chronic tonsillitis. Acute infectious diseases (such as scarlet fever, measles, flu, diphtheria, etc.) can cause chronic tonsillitis, and sinus infections in the nasal cavity can also be accompanied by this disease. The most common pathogens are Streptococcus and Staphylococcus. Clinical manifestations include frequent throat discomfort, foreign sensation, dryness, itching, irritating cough, bad breath and other symptoms.
D. Otitis media
Otitis media is an inflammatory disease that affects all or part of the middle ear (including the Eustachian tube, tympanum, tympanic sinus, and mastoid air chamber), and it is more common in children. It can be divided into two categories: non-purulent and suppurative. Non-suppurative ones include secretory otitis media, baro-injury otitis media, etc. Purulent ones are divided into acute and chronic. Specific inflammation is too rare, such as tuberculous otitis media.
Pharyngitis is a non-specific inflammation of the pharynx. It is a general term for inflammation caused by various microorganisms infecting the pharynx. It can exist alone, or coexist with rhinitis, tonsillitis and laryngitis, or be a prodromal symptom of certain diseases. It can be divided into acute pharyngitis and chronic pharyngitis. Acute pharyngitis is an acute inflammation of the pharyngeal mucosa and submucosal tissues. Pharyngeal lymphoid tissues are often involved. The inflammation can be localized in the early stage.
As the disease progresses, it can often involve the entire pharyngeal cavity. It is more common at the turn of autumn and winter, and winter and spring. The main manifestations are dryness, burning, pain in the pharynx, obvious pain in swallowing, and hyperemia and swelling in the pharynx. Chronic pharyngitis can be divided into chronic simple pharyngitis, chronic hypertrophic pharyngitis and atrophic pharyngitis.
Chronic simple pharyngitis is more common. The lesions are mainly in the mucosal layer, manifested by chronic congestion of the pharyngeal mucosa, and hyperplasia of the mucosa and submucosal connective tissue. And Mucous glands have hypertrophied, hypersecretion, and increased mucus secretion. Patients often spit out sticky sputum in the pharynx, or feel a foreign body sensation in the pharynx, can't. This disease is more common in adults, with a long course of disease, easy to relapse, stubborn and difficult to cure.
The adult dose is 125 to 500 mg (200,000 to 800,000 units)/time, once every 6 to 8 hours.
Child dose: once every 4 hours, 2.5～9.3 mg (4167～15000 units)/kg each time; once every 6 hours, 3.75-14 mg (6250～22500 units)/kg each time; once every 8 hours, 5～18.7 mg (8333～30000 units)/kg each time.
Penicillin v has the same antibacterial spectrum as penicillin, but its effect is stronger than penicillin. However, the side effects and contraindications of penicillin v should be noted when applying this drug.