Pyostacin (Pristinamycin) 500 mg, 16 tablets: profile, composition and research
Reference page for Pyostacin (Pristinamycin) 500 mg, 16 tablets. Active substance: Пристинамицин / Pristinamycin.
- What it is: pristinamycin, an antibiotic of the naturally occurring streptogramin class.
- Presentation: film-coated tablets of 500 mg, 16 tablets per pack.
- Status: prescription-only medicine.
- Research: work on its spectrum and on combinations with other antibiotics, links below.
- Where to buy: APV Pharmacy (price and availability there).
Key facts
| Active substance | Pristinamycin |
|---|---|
| Form | Film-coated tablets |
| Strength | 500 mg per tablet |
| Pack size | 16 tablets |
| Route | Oral, taken with meals |
| Category | Prescription medicine |
| Article (SKU) |
What pristinamycin is
Pyostacin is an oral antibiotic whose active substance is pristinamycin, a natural compound of the streptogramin class. It was isolated from soil bacteria of the genus Streptomyces and has been used in medicine for decades.
The product is supplied as film-coated tablets of 500 mg. A pack holds 16 tablets, sized for a short, intensive course.
Interest in this group follows the rise of resistance to familiar antibiotics. Pristinamycin works differently from most common classes, so cross-resistance is seen less often.
How it works
Two substances in one
Pristinamycin is a mixture of two parts, IA and IIA. The first is a macrocyclic lactone, the second a polyunsaturated macrolactone. On its own each only halts bacterial growth; together they form a complex with a stronger effect.
The target in the bacterial cell
Both components bind to different sites on the bacterial 50S ribosome subunit, the machinery that assembles proteins.
A double blockade
Protein synthesis is interrupted at two steps: first peptide-bond formation is disrupted, then the growing protein chain cannot move on. This two-sided interference lowers the chance that resistance appears during treatment.
What that means in practice
Because of the dual mechanism, pristinamycin stays active against some strains that are resistant to macrolides and other classes.
Activity spectrum and approved uses
The medicine acts on Gram-positive cocci, among them pneumococci, streptococci and staphylococci, including strains resistant to methicillin. Among Gram-negative respiratory pathogens it covers Haemophilus influenzae and Moraxella catarrhalis, and among intracellular ones Mycoplasma pneumoniae and Chlamydia pneumoniae.
An important limitation: pristinamycin acts poorly on group A beta-haemolytic streptococcus, the cause of strep throat. Clinical work shows it eradicates the organism less often than amoxicillin, so it is not used in acute tonsillitis.
According to the prescribing information the medicine is indicated in adults and children for upper and lower respiratory tract infections, including acute sinusitis, bacterial exacerbation of chronic bronchitis and mild to moderate community-acquired pneumonia, as well as for skin and soft tissue infections.
Tablets are taken with meals: absorption improves and gastrointestinal discomfort is less frequent. The tablet form is not given to children under 6 because of the risk of choking. The dose and the length of the course are set by a physician.
What the publications show
A review in the Journal of Antimicrobial Chemotherapy, 'Old drug, new tricks', examines where pristinamycin stands today. A paper in BMC Infectious Diseases studies its combinations against methicillin-resistant Staphylococcus aureus in skin infections.
A network meta-analysis of randomised trials published in Archives of Dermatological Research compares the efficacy and safety of first- and second-line antibiotics in cellulitis and erysipelas. Adverse reactions are also described in the literature, including sideroblastic anaemia and toxic epidermal necrolysis during pristinamycin treatment.
Published research
Primary sources, verified against PubMed:
- Pristinamycin: old drug, new tricks?, PubMed 24891428 (The Journal of antimicrobial chemotherapy, 2014).
- Pristinamycin-antibiotic combinations against methicillin-resistant Staphylococcus aureus recovered from skin infections., PubMed 40958109 (BMC infectious diseases, 2025).
- Efficacy and safety of first- and second-line antibiotics for cellulitis and erysipelas: a network meta-analysis of randomized controlled trials., PubMed 39240378 (Archives of dermatological research, 2024).
- Pristinamycin-induced sideroblastic anaemia., PubMed 37311214 (The Journal of antimicrobial chemotherapy, 2023).
Listed for reference. Publication of a study is not a claim about this particular product.
Precautions
- This is a prescription medicine. Prescribing, dosing and monitoring belong to a physician.
- It is not used in case of hypersensitivity to pristinamycin, other streptogramins or the tablet excipients.
- It is contraindicated in wheat allergy: the tablets contain wheat starch. For patients with celiac disease it is considered safe, since gluten is present only in traces.
- It must not be combined with colchicine: co-administration increases its toxicity.
- With immunosuppressants (ciclosporin, tacrolimus and others) blood levels of those drugs and kidney function must be monitored.
- If a generalised rash with fever and pustules appears early in treatment, the medicine is stopped and a doctor contacted urgently.
- An unfinished course of antibiotics helps resistant bacteria spread.
Frequently asked
Is Pyostacin a prescription medicine?
Yes. It is a prescription antibacterial medicine.
Why does this page not give a dosing schedule?
The regimen depends on the type of infection, the patient's age and condition. A physician sets it.
Can the tablets be taken without food?
The prescribing information requires taking them with meals: absorption improves and stomach discomfort is less likely.
Is it suitable for strep throat?
No. Clinical work shows it is inferior to amoxicillin against group A streptococcus infection.
Where does the order ship from?
Shipping and customs handling are described on the APV Pharmacy delivery page.