Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2019 Publisher: Pfizer Limited, Ramsgate Road, Sandwich, Kent, CT13 9NJ, United Kingdom
Because of lower absorption levels and shorter retention time in the body, Salazopyrin Suppositories give rise to fewer adverse events than equivalent treatment by mouth. However, because of the theoretical possibility that serious adverse events can arise from treatment from either route, the details below are based on adverse event reports to both oral and rectal treatment.
Complete blood counts, including differential white cell count and liver function tests, should be performed before starting sulfasalazine, and every second week during the first three months of therapy. During the second three months, the same tests should be done once monthly and thereafter once every three months, and as clinically indicated. Assessment of renal function (including urinalysis) should be performed in all patients initially and at least monthly for the first three months of treatment. Thereafter, monitoring should be performed as clinically indicated. The patient should also be counselled to report immediately with any sore throat, fever, malaise, pallor, purpura, jaundice or unexpected non-specific illness during sulfasalazine treatment, this may indicate myelosuppression, haemolysis or hepatoxicity. Treatment should be stopped immediately while awaiting the results of blood tests. Please see section 4.4 “Interference with laboratory testing”.
Sulfasalazine should not be given to patients with impaired hepatic or renal function or with blood dyscrasias, unless the potential benefit outweighs the risk.
Sulfasalazine should be given with caution to patients with severe allergy or bronchial asthma.
Use in children with the concomitant condition systemic onset juvenile rheumatoid arthritis may result in a serum sickness like reaction; therefore sulfasalazine is not recommended in these patients.
Since sulfasalazine may cause haemolytic anaemia, it should be used with caution in patients with G-6-PD deficiency.
Oral sulfasalazine inhibits the absorption and metabolism of folic acid and may cause folic acid deficiency (see section 4.6), potentially resulting in serious blood disorders (e.g., macrocytosis and pancytopenia), this can be normalised by administration of folic acid or folinic acid (leucovorin).
Because sulfasalazine causes crystalluria and kidney stone formation, adequate fluid intake should be ensured during treatment.
Oligospermia and infertility may occur in men treated with sulfasalazine. Discontinuation of the drug appears to reverse these effects within 2 to 3 months. As far as is known oligospermia has not occurred during therapy per rectum.
Several reports of possible interference with measurements, by liquid chromatography, of urinary normetanephrine causing a false-positive test result have been observed in patients exposed to sulfasalazine or its metabolite, mesalamine/ mesalazine.
Sulfasalazine or its metabolites may interfere with ultraviolet absorbance, particularly at 340 nm, and may cause interference with some laboratory assays that use NAD or NADP to measure ultraviolet absorbance around that wavelength. Examples of such assays may include urea, ammonia, LDH, α-HBDH and glucose. It is possible that alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase-muscle/brain (CK-MB), glutamate dehydrogenase (GLDH), or thyroxine may also show interference when sulfasalazine treatment is given at high doses. Consult with the testing laboratory regarding the methodology used. Caution should be exercised in the interpretation of these laboratory results in patients who are receiving sulfasalazine. Results should be interpreted in conjunction with clinical findings.
There have been no adverse interactions reported, due to the drug largely remaining confined to the rectum. However, there is a potential for interaction as follows:
Reduced absorption of digoxin, resulting in non-therapeutic serum levels, has been reported when used concomitantly with oral sulfasalazine.
Sulfonamides bear certain chemical similarities to some oral hypoglycaemic agents. Hypoglycaemia has occurred in patients receiving sulfonamides. Patients receiving sulfasalazine and hypoglycaemic agents should be closely monitored.
Due to inhibition of thiopurine methyltransferase by salazopyrin, bone marrow suppression and leucopenia have been reported when the thiopurine 6-mercaptopurine or it’s prodrug, azathioprine, and oral salazopyrin were used concomitantly.
Coadministration of oral sulfasalazine and methotrexate to rheumatoid arthritis patients did not alter the pharmacokinetic disposition of the drugs. However, an increased incidence of gastrointestinal adverse events, especially nausea, was reported.
Reproduction studies in rats and rabbits have revealed no evidence of harm to the foetus. Published data regarding use of sulfasalazine in pregnant women have revealed no evidence of teratogenic hazards. If sulfasalazine is used during pregnancy, the possibility of foetal harm appears remote. Oral sulfasalazine inhibits the absorption and metabolism of folic acid and may cause folic acid deficiency. Because the possibility of harm cannot be completely ruled out, sulfasalazine should be used during pregnancy only if clearly needed.
Sulfasalazine and sulfapyridine are found in low levels in breast milk. Patients should avoid breastfeeding while taking this medicine. There have been reports of bloody stools or diarrhoea in infants who were breastfeeding from mothers on sulfasalazine. In cases where the outcome was reported, bloody stools or diarrhoea resolved in the infant after discontinuation of sulfasalazine in the mother.
No specific effects.
The following have been reported to sulfasalazine given orally or rectally. The drug rectally is well tolerated. Overall, about 75% of adverse drug reactions occur within three months of starting therapy and over 90% by six months. Some undesirable effects are dose-dependent and symptoms can often be alleviated by reduction of the dose.
Sulfasalazine is split by intestinal bacteria to sulfapyridine and 5-amino salicylate so adverse drugs reactions to either sulfonamide or salicylate are possible. Patients with slow acetylator status are more likely to experience adverse drug reactions related to sulfapyridine. The most commonly encountered adverse drugs reactions are nausea, headache, rash, loss of appetite and raised temperature.
The adverse reactions observed during clinical studies conducted with Sulfasalazine have been provided in a single list below by class and frequency (very common (≥1/10); common (≥1/100 to< 1/10); uncommon (≥1/1000 to < 1/100). Where an adverse reaction was seen at different frequencies in clinical studies, it was assigned to the highest frequency reported.
Additional reactions reported from post-marketing experience are included as frequency Not known (cannot be estimated from the available data) in the list below.
Not known: Pseudomembranous colitis
Common: Leukopenia
Uncommon: Thrombocytopenia*
Not known: Agranulocytosis, aplastic anaemia, haemolytic anaemia, Heinz body anaemia, hypoprothrombinaemia, lymphadenopathy, macrocytosis, megaloblastic anaemia, methaemoglobinaemina, neutropenia, pancytopenia
Not known: Anaphylaxis, polyarteritis nodosa, serum sickness
Not known: Loss of appetite
Common: Insomnia
Uncommon: Depression
Not known: Hallucinations
Common: Dizziness, headache, taste disorders
Uncommon: Convulsions
Not known: Aseptic meningitis, ataxia, encephalopathy, peripheral neuropathy, smell disorders
Common: Tinnitus
Uncommon: Vertigo
Common: Conjuctivial and scleral injection
Not known: Allergic myocarditis, cyanosis, pericarditis
Uncommon: Vasculitis
Common: Cough
Uncommon: Dyspnoea
Not known: Fibrosing alveolitis, eosinophilic infiltration, interstitial lung disease
Very Common: Gastric distress, nausea
Common: Abdominal pain, diarrhoea, vomiting, stomatitis
Not known: Aggravation of ulcerative colitis, pancreatitis, parotitis
Not known: Hepatic failure, fulminant hepatitis, hepatitis*
Common: Pruritus
Uncommon: Alopecia, urticaria
Not known: Epidermal necrolysis (Lyell’s syndrome), Stevens-Johnson syndrome, drug rash with eosinophilia and systemic symptoms (DRESS), toxic pustuloderma, erythema, exanthema, exfoliative dermatitis, periorbital oedema, lichen planus, photosensitivity
Common: Arthralgia
Not known: Systemic lupus erythematosus
Common: Proteinuria
Not known: Nephrotic syndrome, interstitial nephritis, crystalluria*, haematuria
Not known: Reversible oligospermia*
Common: Fever
Uncommon: Facial oedema
Not known: Yellow discoloration of skin and body fluids
Uncommon: Elevation of liver enzymes
Not known: Induction of autoantibodies
* See Section 4.4 for further information
Reporting suspected adverse reactions after authorization of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
Certain types of extended wear soft contact lenses may be permanently stained during therapy.
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