Quantitative analysis of drug losses administered via nasogastric tube--In vitro study.

Purpose: Drug administration through nasogastric tube (NGT) is a standard practice but the real amount of the delivered drug is unknown. Therefore, we designed a study to determine the losses of various dosage forms administered by different methods through NGT.

Methods: In vitro model was used. Five different administration methods (A-E) and six dosage forms (simple compressed tablets - T/S; film coated tablets - T/FC; enteric coated tablets - T/EC; capsules with powder filling - C/P; capsules containing extended release pellets - C/ER; capsules containing gastro-resistant pellets - C/GR) were investigated. Measurement was repeated six times for each drug-method combination. The overall losses were determined by gravimetry. In method A partial losses associated with each step of drug administration were also determined.

Results: Significant drug losses were measured (4-38%). Only methods A (crushing-beaker-syringe-water-NGT) and B (crushing-water-syringe-NGT) were suitable for administration of all tested dosage forms. Method B proved the most effective for all kinds of tablets and C/GR (p<0.05) and tended to be more effective also for C/ER (p=0.052) compared to method A. C/P showed minimal losses for both tested methods (B and E). Flushing of the drug through NGT causes major losses during drug administration compared to crushing and transfer (p<0.05). All methods for intact pellets (C-E) were found inappropriate for clinical practice due to NGT clogging.

Conclusions: Choosing a suitable administration method can significantly affect the amount of drugs delivered through NGT.