Swallowing safety of oral liquid medications: assessment using the International Dysphagia Diet Standardisation Initiative framework

Background This study characterises commercially available oral liquid medications in terms of thickness and textural suitability for safe swallowing by patients with dysphagia for inclusion in the fourth edition of Don't Rush to Crush (DRTC), published by the Society of Hospital Pharmacists of Australia. Aim This study had two aims. The first was to use the International Dysphagia Diet Standardisation Initiative (IDDSI) testing methods to evaluate and document the thickness and textural properties of commercially available liquid medications in Australia to be included in the fourth edition of DRTC. The second aim was to determine the volume of oral liquids that could be mixed into medication lubricants while maintaining the lubricant's IDDSI classification. Methods A total of 121 different oral liquid medications were assessed for flow through a syringe and consistency on a fork according to the IDDSI framework to classify them as Level 0 (Thin), Level 1 (Slightly Thick), Level 2 (Mildly Thick), Level 3 (Moderately Thick), or Level 4 (Extremely Thick). Results The 121 liquid medications were classified as Level 0 (n = 47, 39%), Level 1 (n = 20, 16%) or Level 2 (n = 54, 45%). Although 18 (15%) of the liquids appeared to be thicker than Level 2 according to the IDDSI flow test, the fork drip test clearly identified them as thinner than Level 3. We considered thickening low-volume doses using an IDDSI Level 4 medication lubricant; for 97% (n = 112) of 115 oral liquid medications it was possible to incorporate 2.5 mL within two pumps (10 g) of Gloup Forte (vanilla flavour) and retain the IDDSI Level 4 classification. Conclusion Commercially available oral liquids are classified as IDDSI Level 0, 1, or 2. While they present no problem to healthy people, most patients with dysphagia are unlikely to safely swallow these fluids. Evaluation of the swallowing function of dysphagic patients prior to use of oral medications is essential.