Medicines by sublingual and nasogastric routes

Medicines designed and formulated to be swallowed and absorbed in the stomach and small bowel are not necessarily equally effective when given in a different way – the two common options considered are sublingual and crushed and administered via nasogastric tube.

Sublingual

Absorption of many medications is affected by pH, and the effect of simply popping a pill under the tongue or crushing it and placing it in the mouth is unpredictable. A third option sometimes considered is the buccal use of intravenous formulations, either because of difficulties with venous access (e.g. in outpatients of because of a desire for the medicine to be administered by a lay person (e.g. home management of an epileptic seizure

Sublingual captopril – just a bitter after taste

Absorption is pH dependent, and be careful of just taking headline findings of slightly more rapid Tmax without checking whether the pills were simply crushed, or if they were administered with a buffer. In general, the findings are a bit mixed, and all fairly dated. A small (70 patient) 2018 RCT from Iran found a ‘significant’ difference in blood pressure between oral and sublingual, but in real terms this was an absolute 4% difference in percentage drop in systolic (8% vs 4% at 10 mins and 10% vs 6% drop at 20 mins) which had evened out at 30 minutes. It is highly unlikely that this difference has any clinical value.¹. Another earlier study which had clear quality issues (sequential allocation although listed as a RCT) enrolled 212 hypertensive patients and again stated that there were statistically significant differences – these turned out to be a 5-6 mmHg difference in systolic BP at 10 mins, and a 3 mmHg difference at 30 minutes – very unlikely to be of any clinical relevance. All had again evened out by one hour.
² A third observational study of 71 patients found no benefit from sublingual administration³ A 2021 systematic review found the same dated literature and confirmed the very modest short term absolute reductions in BP⁴.

Sublingual nifedipine

This is probably no longer a major concern although a popular pastime previously. Current recommendations are against its use, and have been so for nearly two decades⁵ The bottom line is that oral absorption is nearly as good as sublingual, or possibly even superior⁶, so the sublingual route (and large stat oral doses) make little sense.

Nasogastric medication administration

There are some clear issues with crushing medicines meant to be swallowed whole. A small ICU study (10 patients) found that the majority given crushed TB combination pills had subtherapeutic rifampicin concentrations, although the other drugs were adequately absorbed⁷. Valproate is another bad choice for crushing, and consider giving the syrup 8 hourly rather than crushed sustained release tablets.

ARVs

Efavirenz is water insoluble so the manufacturer recommends that it not be administered crushed. This applies therefore to any combination tablet containing this agent. Crushed dolutegravir and tenofovir are options with probable adequate absorption, and other possibilities are abacavir and lamivudine syrups.⁸

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1. Mousavi, Mehdi & Razavianzadeh, Nasrin & Armin, Mania & Dashti, Maryam. (2018). Sublingual Versus Oral Captopril for Decreasing Blood Pressure in Hypertension Urgency. Iranian Red Crescent Medical Journal. In Press. 10.5812/ircmj.61606.  ↩

2. Kaya A, Tatlisu MA, Kaplan Kaya T, Yildirimturk O, Gungor B, Karatas B, Yazici S, Keskin M, Avsar S, Murat A. Sublingual vs. Oral Captopril in Hypertensive Crisis. J Emerg Med. 2016 Jan;50(1):108-15. doi: 10.1016/j.jemermed.2015.07.017. Epub 2015 Sep 26. PMID: 26409670. ↩

3. Karakiliç E, Büyükcam F, Kocalar G, Gedik S, Atalar E. Same effect of sublingual and oral captopril in hypertensive crisis. Eur Rev Med Pharmacol Sci. 2012 Nov;16(12):1642-5. PMID: 23161035. ↩

4. Ulfiarakhma, Dela1; Mulawarman R, Trifitriana M. Sublingual versus oral captopril for blood pressure reduction in hypertensive urgency: a systematic review and meta-analysis. Journal of Hypertension.2021;39:e13 doi: 10.1097/01.hjh.0000752556.41180.65  ↩

5. Grossman E, Messerli FH, Grodzicki T, Kowey P. Should a Moratorium Be Placed on Sublingual Nifedipine Capsules Given for Hypertensive Emergencies and Pseudoemergencies? JAMA. 1996;276(16):1328–1331. doi:10.1001/jama.1996.03540160050032  ↩

6. Brown, G.R., Fraser, D.G., Castile, J.A., Gaudreault, P., Platt, D.R. and Friedman, P.A. Nifedipine serum concentrations following sublingual and oral doses. International Journal of clinical pharmacology, therapy, and toxicology.1986;24(6):283-286 ↩

7. Koegelenberg CF, Nortje A, Lalla U, Enslin A, Irusen EM, Rosenkranz B, Seifart HI, Bolliger CT. The pharmacokinetics of enteral antituberculosis drugs in patients requiring intensive care. South African Medical Journal. 2013;103(6):394-8 ↩

8. Moore SE, Huesgen E, Howe Z. Sustained virologic suppression with abacavir, emtricitabine, and crushed dolutegravir and tenofovir alafenamide in a patient with HIV and eosinophilic esophagitis. International Journal of STD & AIDS. 2020;31(3):285-287. doi:10.1177/0956462419895690 ↩

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