McKenna's Pharmacology for Nursing, 2e

C H A P T E R 5 2 Drugs affecting the urinary tract and the bladder 827

TABLE 52.4

DRUGS IN FOCUS Other drugs affecting the urinary tract and bladder

Drug name

Dosage/route

Usual indications

Bladder protectant

100 mg PO t.d.s

Relief of bladder pain or discomfort associated with interstitial cystitis

pentosan polysulfate sodium (Elmiron)

bladder wall. Pentosan polysulfate sodium ( Elmiron ) is used to coat or adhere to the bladder mucosal wall and protect it from irritation related to solutes in urine. It is not available in New Zealand. Therapeutic actions and indications Pentosan polysulfate sodium, available for oral administration, is a heparin-like compound that has anticoagulant and fibrinolytic effects. This drug adheres to the bladder wall mucosal membrane and acts as a buffer to control cell permeability, preventing irritating solutes in the urine from reaching the bladder wall cells (see Figure 52.1). It is used specifically to decrease the pain and discomfort associated with interstitial cystitis , a chronic inflammation of the interstitial connective tissue of the bladder that may extend into deeper tissue. See Table 52.4. Pharmacokinetics After oral administration, very little of this drug is absorbed (3%). It is distributed to the GI tract, liver, spleen, skin, bone marrow and periosteum. It under- goes metabolism in the liver and spleen and is excreted in urine. It has a half-life of 4.8 hours. It is not known whether the drug crosses the placenta or enters breast milk due to the lack of adequate studies of the effects of the drug during pregnancy or breastfeeding; caution should be used if the drug is needed during pregnancy or breastfeeding. Contraindications and cautions Pentosan should not be used with any condition that involves an increased risk of bleeding (surgery, preg- nancy, anticoagulation, haemophilia) because of its heparin-like effects. It is also contraindicated in the presence of a history of heparin-induced thrombocyto- penia, which could recur with use of this drug. Caution should be used in individuals with hepatic or sphenic dysfunction, which could be affected by the heparin-like actions of the drug , and in pregnant or breastfeeding women because of the potential for adverse effects on the fetus or neonate. Adverse effects Adverse effects associated with pentosan use include bleeding that may progress to haemorrhage (related to

the drug’s heparin effects), headache, alopecia (seen with heparin-type drugs) and GI disturbances related to local irritation of the GI tract with administration. Clinically important drug–drug interactions There is a potential for increased bleeding risks if this drug is combined with anticoagulants, aspirin or non-steroidal anti-inflammatory drugs (NSAIDs). If such a combination is used, the person should be monitored very closely for any signs of bleeding, and appropriate dose adjustments should be made to the anticoagulants, aspirin or NSAID. Prototype summary: Pentosan polysulfate sodium Indications: Relief of bladder pain associated with interstitial cystitis. Actions: Adheres to the bladder wall mucosal membrane and acts as a buffer to control cell permeability, preventing irritating solutes in the urine from reaching the bladder wall cells. Pharmacokinetics: Route Onset Oral Varies T 1/2 : 4.8 hours; metabolised in the liver and spleen and excreted in urine. Adverse effects: Bleeding, headache, alopecia, GI disturbances.

Care considerations for people receiving a bladder protectant

Assessment: History and examination

■ ■ Assess for contraindications or cautions : history of allergy to these drugs to prevent hypersensitivity reactions or renal insufficiency, which could interfere with excretion of the drug ; history of bleeding abnormalities, splenic disorders or hepatic dysfunction, which could be exacerbated by the heparin-like effect s; and current status of pregnancy and breastfeeding, which require cautious use of this drug.