Fthalazole, tablets 500 mg, 10 pcs.

Fthalazole, like other sulfonamide drugs similar in structure to PABA, by the principle of competitive relationships interferes with its inclusion in the synthesis of folic acid of the microbial cell. This leads to disruption of folic acid formation, which is involved in the synthesis of purine and pyrimidine bases, on which the growth and development of microorganisms depends. Phthalazole has the most pronounced bacteriostatic effect on vegetative forms of microbes. This effect develops gradually, since the microbial cell has some PABA reserves.

In addition, the degree of affinity of phthalazole with dihydrofolic acid synthetase, the enzyme that limits folic acid formation, is much weaker compared to PABA. Therefore, phthalazole must be administered in doses high enough to prevent the microorganisms from using the PABA contained in the tissues. Otherwise, resistant strains of pathogens may form that are not amenable to further exposure to sulfonamide drugs.

In addition to its antibacterial effect, phthalazole, like other sulfonamide drugs, has an anti-inflammatory effect, which is associated with its ability to limit leukocyte migration, reduce the total number of migrating cellular elements and partially stimulate GCS production.

The spectrum of antimicrobial action of phthalazole, like other sulfonamides, is narrower than that of antibiotics. Sulfonamides have bacteriostatic action against Streptococcus, Pneumococcus, Staphylococcus, Meningococcus, Gonococcus, Escherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae, Proteus vulgaris and several major viruses – agents of trachoma and follicular conjunctivitis.

Indications

Active ingredient

Composition

Active ingredient:

Phthalylsulfatiazole 0.5 g.

Auxiliary substances:

potato starch,

calcium stearate,

polyvinylpyrrolidone low molecular weight medical,

aerosil.

How to take, the dosage

In acute dysentery: adults – orally on days 1-2 by 1 g 6 times/day (every 4 hours – 1 g), on days 3-4 – 1 g 4 times/day (every 6 hours – 1 g), on days 5-6 – 1 g 3 times/day (every 8 hours – 1 g).

The average course dose is 25-30 g. After 5-6 days the second cycle of treatment is carried out: days 1-2 – 1 g 5 times/day (every 4 hours, at night – 8 hours), days 3-4 – 1 g 4 times/day (do not give at night), day 5 – 1 g 3 times/day. The total dose in the second cycle is 21 g, and in a mild course – 18 g. Higher doses for adults: single dose – 2 g, daily – 7 g. Children under 3 years old – 0.2 g/kg/day in 3 doses during 7 days children over 3 years old – 0.4-0.75 g (depending on age) per day.

Other infections: in adults during the first 2-3 days – 1-2 g every 4-6 hours, on the next 2-3 days – half dose. Children are prescribed 0.1 g/kg/day in equal doses every 4 hours (with a night break), on the following days – 0.2-0.5 g every 6-8 hours.

Interaction

PASC (para-aminosalicylic acid) and barbiturates – sulfonamide activity is increased. Salicylates – increased activity and toxicity. Methotrexate and Diphenin – increased toxicity. Thioacetasone, levomycetin – possibility of agranulocytosis increases.

Nitrofurans – increased risk of methemoglobinemia. Indirect anticoagulants – increased anticoagulant effect. Oxacillin – reduces the activity of the antibiotic.

The combined use of Fthalazole with acids and acid-reacting preparations, hexamethylentetramine, adrenaline solution is not advisable because they are chemically incompatible.

In the combined use of Fthalazole with drugs containing esters of para-aminobenzoic acid (novocaine, anesthesin, dicaine), the antibacterial activity of sulfonamide is inactivated by a competitive mechanism. The effect is enhanced by antibiotics and well-absorbed sulfonamides.

Special Instructions

If necessary, the drug is combined with antibiotics.

Contraindications

Side effects

In case of individual hypersensitivity to sulfonamides, allergic reactions are possible.