BNF for Children 2011-2012

BNFC 2011–2012 6.5.2 Posterior pituitary hormones and antagonists 385Zomacton c (Ferring) LInjection, powder for reconstitution, somatropin(rbe), net price 4-mg (12-unit) vial (with diluent) =£79.69. For use with ZomaJet 2 Vision c D needlefreedevice (available free of charge from clinics) orwith needles and syringes; 10-mg (30-unit) vial (withdiluent) = £199.23, for use with ZomaJet Vision X cD needle-free device (available free of charge fromclinics) or with needles and syringes. For subcutaneousinjectionExcipients include benzyl alcohol (in 4-mg vial) (avoid in neonates, seeExcipients, p. 2)Hypothalamic hormonesGonadorelin when injected intravenously in post-pubertalgirls leads to a rapid rise in plasma concentrationsof both luteinising hormone (LH) and follicle-stimulatinghormone (FSH). It has not proved to be very helpful,however, in distinguishing hypothalamic from pituitarylesions. It is used in the assessment of delayed orprecocious puberty.Other growth hormone stimulation tests involve the useof insulin, glucagon, arginine, and clonidine [all unlicenseduses]. The tests should be carried out in specialistcentres.GONADORELIN(Gonadotrophin-releasing hormone; GnRH;LH–RH)Cautions pituitary adenomaPregnancy avoidBreast-feeding avoidSide-effects rarely nausea, headache, abdominalpain, increased menstrual bleeding; rarely, hypersensitivityreaction on repeated administration oflarge doses; irritation at injection siteLicensed use not licensed for use in children under 1yearIndication and doseAssessment of anterior pituitary function;assessment of delayed puberty. By subcutaneous or intravenous injectionChild 1–18 years 2.5 micrograms/kg (max.100 micrograms) as a single doseHRF c (Intrapharm) AInjection, powder for reconstitution, gonadorelin. Netprice 100-microgram vial (with diluent) = £13.72(hosp. only)Excipients include benzyl alcohol (avoid in neonates, see Excipientsp. 2)6.5.2 Posterior pituitaryhormones andantagonistsPosterior pituitary hormonesDiabetes insipidus Diabetes insipidus is caused byeither a deficiency of anti-diuretic hormone (ADH, vasopressin)secretion (cranial, neurogenic, or pituitary diabetesinsipidus) or by failure of the renal tubules to reactto secreted antidiuretic hormone (nephrogenic diabetesinsipidus).Vasopressin (antidiuretic hormone, ADH) is used in thetreatment of pituitary diabetes insipidus as is its analoguedesmopressin. Dosage is tailored to produce aregular diuresis every 24 hours to avoid water intoxication.Treatment may be required permanently or for alimited period only in diabetes insipidus following traumaor pituitary surgery.Desmopressin is more potent and has a longer durationof action than vasopressin; unlike vasopressin it has novasoconstrictor effect. It is given by mouth or intranasallyfor maintenance therapy, and by injection in thepostoperative period or in unconscious patients.Desmopressin is also used in the differential diagnosisof diabetes insipidus; following an intramuscular orintranasal dose, restoration of the ability to concentrateurine after water deprivation confirms a diagnosis ofpituitary diabetes insipidus. Failure to respond suggestsnephrogenic diabetes insipidus. Fluid input must bemanaged carefully to avoid hyponatraemia; this test isnot usually recommended in young children.In nephrogenic and partial pituitary diabetes insipidusbenefit may be gained from the paradoxical antidiureticeffect of thiazides (section 2.2.1) e.g. chlorothiazide 10–20 mg/kg (max. 500 mg) twice daily.Other uses Desmopressin is also used to boost factorVIII concentration in mild to moderate haemophilia andin von Willebrand’s disease; it is also used to test fibrinolyticresponse. For a comment on use of desmopressinin nocturnal enuresis see section 7.4.2.Vasopressin infusion is used to control variceal bleedingin portal hypertension, before introducing more definitivetreatment. Terlipressin, a derivative of vasopressin,and octreotide are used similarly but experience inchildren is limited.DESMOPRESSINCautions see under Vasopressin; less pressor activity,but still considerable caution in cardiovascular diseaseand in hypertension (not indicated for nocturnalenuresis or nocturia in these circumstances); alsoconsiderable caution in cystic fibrosis; in nocturia andnocturnal enuresis limit fluid intake from 1 hourbefore dose until 8 hours afterwards; in nocturiaperiodic blood pressure and weight checks needed tomonitor for fluid overload; interactions: Appendix 1(desmopressin)For cautions specifically relating to the use ofdesmopressin in nocturnal enuresis see section 7.4.2Hyponatraemic convulsions Patients being treated for primarynocturnal enuresis should be warned to avoid fluidoverload (including during swimming) and to stop takingdesmopressin during an episode of vomiting or diarrhoea(until fluid balance normal). The risk of hyponatraemicconvulsions can also be minimised by keeping to therecommended starting doses and by avoiding concomitantuse of drugs which increase secretion of vasopressin (e.g.tricyclic antidepressants)Contra-indications cardiac insufficiency and otherconditions treated with diuretics; psychogenic polydipsiaand polydipsia in alcohol dependenceRenal impairment use with caution; antidiureticeffect may be reduced6 Endocrine system