McKenna's Drug Handbook for Nursing & Midwifery, 7e

782      Musculoskeletal drugs

CV: tachycardia, erratic blood pressure. ENT: speech disturbance. Eye: excessive lacrimation, diplopia, visual disturbances. GI: anorexia, constipation, cramping, dys­ phagia, metallic taste, severe diarrhoea, GI bleeding. GU: urinary frequency, haematuria, incontin­ ence, nocturia, dysuria, crystalluria, difficult erection, urine retention, increased urea level. Hepatic: hepatitis , increased ALT, AST, alkaline phosphatase, LDH and total serum bilirubin levels. Musculoskeletal: myalgia, back pain, muscle weakness . Respiratory: pleuraleffusionwithpericarditis. Skin: eczematouseruption,pruritus,urticaria, abnormal hair growth, sweating. Other: chills. Interactions Drug-drug. CNSdepressants: Increased CNS depression. Avoid use together. Oestrogens: Possible increased risk of hepatotoxicity. Use together cautiously. Verapamil: Possible CV collapse with IV verapamil. Stop verapamil before administ­ ering IV dantrolene. Drug-lifestyle. Alcohol use: Increased CNS depression. Caution person to avoid alcohol use. Sunexposure: Photosensitivity and increased risk of sunburn. Advise person to take precautions and to avoid excessive sunlight. Contraindications Contraindicated in individuals when spasticity is used tomaintainmotor function orforspasms inrheumaticdisorders; inthose with uppermotor neuron disorders or active hepatic disease; and in women who are breastfeeding. care considerations • Use cautiously in individuals with severely impaired cardiac or pulmonary function or pre-existing hepatic disease, inwomen and in individuals older than 35 years.

Children: Initially, 0.5 mg/kg PO b.i.d., increasedtot.i.d.,thenq.i.d.Dosageincreased, p.r.n., by 0.5 mg/kg daily to 3 mg/kg b.i.d. to q.i.d. Maximumdosage is 100 mg q.i.d. ➤ Management of malignant hyperthermia crisis— Adults and children: 1 mg/kg IV initially; dose repeated, p.r.n., up to cumulative dosage of 10 mg/kg. ➤ Prevention or attenuation of malignant hyperthermia crisis in susceptible individuals who require surgery— Adults: 4–8 mg/kg PO daily in three to four divided doses for 1–2 days before procedure. Final dose administered 3–4 hours before procedure. ➤ Prevention of recurrence of malignant hyperthermia crisis— Adults: 4–8 mg/kg daily PO in four divided doses for up to 3 days after hyperthermic crisis. IV administration • Give as soon as malignant hyperthermia reaction is recognised. • Reconstitute each vial by adding 60 mL of sterile water for injection and shaking vial until clear. Do not use a diluent that contains a bacteriostatic agent. • Watch for irritation and infiltration; extravasation can cause tissue damage and necrosis. • Protect contents from light and usewithin 6 hours. Action Acts directly on skeletal muscle to interfere with intracellular calcium movement by decreasing excitation and contraction coupling and reducing muscle strength. Route Onset Peak Duration PO Unknown 5 hrs Unknown IV Unknown Unknown Unknown Adverse reactions CNS: drowsiness, dizziness, fever, light- headedness, malaise, fatigue, headache, confusion, nervousness, insomnia, seizures.

Reactions may be common , uncommon, life-threatening , or commonandlife-threatening.