57 - Mood stabilisers

Mood stabilisers

852 The Maudsley® Prescribing Guidelines in Psychiatry CHAPTER 10 Mood stabilisers Table 10.18 summarises the use of mood stabilisers in bariatric surgery. General summary ■ ■Antipsychotics are not well studied in bariatric surgery. Data are limited to case reports or theoretical concerns. ■ ■Monitor for decreased efficacy. Adjust dose accordingly or consider switching to another antipsychotic. ■ ■Depot antipsychotics avoid the risk of reduced absorption after surgery. Given the limited data on pharmacokinetic changes after surgery and interindividual variability, routinely switching to depot antipsychotics before surgery may not be justified.7 However, depot preparations remain an option for those stabilised on treatment available as a depot or in patients demonstrating signs of reduced bioavailability after surgery. ■ ■Bariatric surgery may contribute additional cardiac stressors to patients with QT prolongation.36 ECG monitoring before and after surgery is recommended. GRDS, gastric reduction duodenal switch; LAI, long-­acting injection; RYGB, Roux-­en-­Y gastric bypass. Table 10.17  (Continued) Table 10.18  Mood stabilisers in bariatric surgery. Medication Summary of evidence and considerations Carbamazepine Carbamazepine CR levels have been observed to both increase and decrease following bariatric surgery.37 In a case series of eight following sleeve gastrectomy, levels were found to be reduced in half the cases, with two resulting in deterioration of previously well-­controlled illness. One case had increased levels.38 Single case report of agranulocytosis possibly related to increased plasma levels after sleeve gastrectomy.38 Baseline plasma carbamazepine levels, FBC, renal function and LFTs with ongoing monitoring recommended.38 Lamotrigine38 Increased, decreased or unchanged lamotrigine levels after bariatric surgery are all possible; monitor for adverse effects and loss of efficacy. Lithium39,40 (see below) Cases of lithium toxicity following RYGB and sleeve gastrectomy have been reported. Switch to an equivalent dose of lithium citrate solution in divided doses. In the preoperative period, plasma levels may be affected by prescribed dietary changes. In the postoperative period, plasma levels may be affected by malabsorption (mainly absorbed via small intestine), fluid shifts and weight loss (lithium clearance increased in obesity). Valproate7,41,42 Single case report suggests that absorption may be significantly reduced after malabsorptive procedures; no data on restrictive procedures. Dose reductions may be necessary after weight loss (plasma levels related to body weight). Switch to liquid preparation before surgery or if malabsorption suspected on enteric-­coated tablets. Avoid CR preparations. Baseline plasma valproate levels, FBC and LFTs with ongoing monitoring recommended. Monitor for clinical signs of poor tolerability, possibly occurring at normal plasma levels. General summary ■ ■The literature on mood stabilisers after bariatric surgery is limited to a few case reports; the use of lithium requires particular care owing to its narrow therapeutic index. ■ ■The absorption of oral contraceptives may be reduced after bariatric surgery.22 In patients prescribed teratogenic mood stabilisers, non-­oral methods of contraception are recommended. CR, controlled release; FBC, full blood count; LFTs, liver function tests; RYGB, Roux-­en-­Y gastric bypass.