Byline: Shrikant. Srivastava, Radhey. Gangwar, Ambrish. Kumar Sir, Response rates to first line antidepressant therapy are abysmally low, and more so in older adults. Ketamine has been used successfully in treatment-resistant depression (TRD), and in nongeriatric population, with response rates at 24 and 72 h postinfusion being 25−85% and 14−72%, respectively.[sup][1] The postulated mechanism of action is through antagonism of N-methyl-D-aspartate receptors.[sup][2] A 65-year-old retired civil servant, living with her husband had fourth episode of depressive illness. In the last 3 years, the illness showed increasing resistance to antidepressant medication(s) with each additional episode. The first episode remitted with escitalopram (10 mg/day), the second episode required higher dosage of escitalopram (40 mg/day), and later, augmentation with amisulpride 25 mg/day, and the third episode remitted with duloxetine (up to 60 mg/day) (as she had relapsed while on escitalopram) and amisulpride 100 mg/day. In the Inter-episode period, the patient had attended all follow-up appointments and continued with prescribed medication. In this episode, she had failed treatment with duloxetine + amisulpride, agomelatine, and agomelatine + amisulpride, respectively. Informed consent was obtained from the patient. Ketamine infusion (0.5 mg/kg diluted in 100 ml of normal saline) was given over 40 min, under the supervision of consultant anesthetist (RSG). Ratings of mood (Hamilton rating scale for depression [HAMD])[sup][3] and side effects (Clinician Administered Dissociative States Scale)[sup][4] were undertaken on morning of the infusion, and 1, 2, and 4 h following infusions, and on in between days of the infusion [labelled as postinfusion days in Table 1]. Four days after the 4[sup]th infusion (HAMD = 10), the patient feeling very much improved subjectively, the ketamine infusions were discontinued, with the provision that further infusions may be required if the depressive symptoms recurred. Agomelatine 50 mg/day was continued through the infusion period and in the follow-up phase.{Table 1} Remission (HAMD The side effects reported with the infusions were − alteration of passage of time (infusion 3, hours 1 and 2) and mild gaps in memory (infusion 4, hour 2). …