Para-Pas - General Information

An antitubercular agent often administered in association with isoniazid. The sodium salt of the drug is better tolerated than the free acid. [PubChem]


Pharmacology of Para-Pas

Aminosalicylic acid is an anti-mycobacterial agent used with other anti-tuberculosis drugs (most often isoniazid) for the treatment of all forms of active tuberculosis due to susceptible strains of tubercle bacilli. The two major considerations in the clinical pharmacology of aminosalicylic acid are the prompt production of a toxic inactive metabolite under acid conditions and the short serum half life of one hour for the free drug. Aminosalicylic acid is bacteriostatic against Mycobacterium tuberculosis (prevents the multiplying of bacteria without destroying them). It also inhibits the onset of bacterial resistance to streptomycin and isoniazid.


Para-Pas for patients

Take all of the aminosalicylic acid that has been prescribed for you even if you start to feel better. Your symptoms may begin to improve before the infection is completely treated, and stopping the medicine before the infection has been completely treated may lead to bacterial resistance. Do not take this medicine if it is brown or purple in color or if the package has swollen. This appearance means that the drug has lost its effectiveness. Aminosalicylic acid will turn brown or purple if left in a hot place, if it is kept in direct sunlight, or if it is exposed to water or moisture. Call your doctor immediately if you experience a fever, a sore throat, unusual bleeding or bruising, or a skin rash.


Para-Pas Interactions

Aminosalicylic acid may decrease the amount of digoxin (Lanoxin, Lanoxicaps) that gets absorbed into your body. In the case that you are taking digoxin while taking aminosalicylic acid, higher doses of digoxin may be needed. Aminosalicylic acid may also decrease the absorption of vitamin B12, which can lead to a deficiency. Therefore you may need to take a vitamin B12 supplement while taking aminosalicylic acid.


Para-Pas Contraindications

Patients with hypersensitivity to any component of this medication should not receive aminosalicylic acid. Patients with severe renal disease will accumulate aminosalicylic acid and its acetyl metabolite but will continue to acetylate, thus leading exclusively to the inactive acetylated form; deacetylation, if any, is not significant. In addition, patients with end stage renal disease should not receive aminosalicylic acid.


Additional information about Para-Pas

Para-Pas Indication: For the treatment of tuberculosis
Mechanism Of Action: There are two mechanisms responsible for aminosalicylic acid's bacteriostatic action against Mycobacterium tuberculosis. Firstly, aminosalicylic acid inhibits folic acid synthesis (without potentiation with antifolic compounds). The binding of para-aminobenzoic acid to pteridine synthetase acts as the first step in folic acid synthesis. Aminosalicylic acid binds pteridine synthetase with greater affinity than para-aminobenzoic acid, effectively inhibiting the synthesis of folic acid. As bacteria are unable to use external sources of folic acid, cell growth and multiplication slows. Secondly, aminosalicylic acid may inhibit the synthesis of the cell wall component, mycobactin, thus reducing iron uptake by M. tuberculosis.
Drug Interactions: Azathioprine The 5-ASA derivative increases the toxicity of thiopurine
Mercaptopurine The 5-ASA derivative increases the toxicity of thiopurine
Thioguanine The 5-ASA derivative increases the toxicity of thiopurine
Food Interactions: Take without regard to meals.
Generic Name: Aminosalicylic Acid
Synonyms: Aminosalicylate Sodium; P-Aminosalicylic Acid; Para-Amino Salicylic Acid; PAS; Para-aminosalicylic acid; 4-aminosalicylic acid; 4-ASA; Amino-PAS; APAS; PASK
Drug Category: Antituberculosis Agents
Drug Type: Small Molecule; Approved

Other Brand Names containing Aminosalicylic Acid: Aminopar; Aminox; Apacil; Deapasil; Entepas; Ferrosan; Gabbropas; Hellipidyl; Kyselina P-Aminosalicylova; Neopasalate; Osacyl; PAS-C; Pamacyl; Pamisyl; Para-Pas; Paramycin; Parasal; Parasalicil; Parasalindon; Pasa; Pasalon; Pasara; Pascorbic; Pasdium; Pasem; Paser; Pasmed; Pasnodia; Pasolac; Propasa; Rezipas; Sanipirol-4; Sanipriol-4;
Absorption: Not Available
Toxicity (Overdose): LD50=4 gm/kg (orally in mice); LD50=3650 mg/kg (orally in rabbits)
Protein Binding: 50-60%
Biotransformation: Hepatic.
Half Life: Not Available
Dosage Forms of Para-Pas: Granule Oral
Chemical IUPAC Name: 4-amino-2-hydroxybenzoic acid
Chemical Formula: C7H7NO3
Aminosalicylic Acid on Wikipedia:
Organisms Affected: Mycobacteria