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Revista da Associação Médica Brasileira

Print version ISSN 0104-4230

Rev. Assoc. Med. Bras. vol.56 no.1 São Paulo  2010 



Drugs and feeding tubes



Milton Luiz GorzoniI, *; Anderson Della TorreII; Sueli Luciano PiresIII

IMédico Doutor e Professor adjunto do Hospital Geriátrico e de Convalescentes Dom Pedro II, São Paulo, SP
IIMédico Assistente do Hospital Geriátrico e de Convalescentes Dom Pedro II, São Paulo, SP
IIIProfessora Instrutora e Diretora Técnica do Hospital Geriátrico e de Convalescentes Dom Pedro II, São Paulo, SP




OBJECTIVE: To define the prevalence of use of drugs incompatible with the enteral route in patients living in long stay institutions for the elderly LTCFs and using feeding tubes.
METHODS: Analysis of prescriptions for LTCF inpatients who are using feeding tubes for longer than 48 hours. Active ingredients, forms of presentation, and possibility of pulverizing the drugs prescribed were compared with data in the literature regarding the feasibility of the enteral administration of drugs.
RESULTS: We found that 57 patients were using feeding tubes (11.2% of the total number of beds). Their mean age was 65.6 ± 16.0 years old, and 32 of them were women and 25 were men. Mean of drugs administered through enteral route: 5.6 ± 2.2. Items included in the prescriptions: 316 divided into 64 drugs, with 129 items (40.8% of the total) and 23 drugs (35.4%) inadequate for this route. The most often prescribed inappropriate drugs: captopril, phenytoin, ranitidine, omeprazole, and B complex. Alternative presentations were found for 15 (65.2%) of the 23 drugs that were not appropriate for enteral administration.
CONCLUSION: Feeding tubes used as a method to administer drugs in LTCF have a significant risk for incompatible prescriptions.

Key words: Drug utilization review. Drug administration routes. Homes for the aged.




The use of feeding tubes has been reported since the pre-Christian Rome, when substances were administrated with the purpose of inducing vomiting. This practice allowed the old Romans to return to their feasts and keep eating, to close deals and to reduce the risk of poisoning. In addition to the attempts to remove foreign bodies, this procedure was also used to administrate emetic and cathartic drugs with the purpose of removing toxins up to the middle of the 18th century. During that period, new and more flexible materials were created, which made it easier to use feeding tubes aimed at helping disabled patients to swallow.1

Around 250 years after the beginning of their use in the clinical practice, feeding tubes are increasingly recommended for the intake of nutrients and administration of drugs when patients are not able to receive drugs and food through the oral route. Regardless of the type of tube, it is worth mentioning that its passage is an invasive procedure that must be carried out according to specific techniques and recommendations.2 Therefore, there is risk of mechanical complications (decubitus lesions, obstructions, misplacements, and tube discard), metabolic complication (electrolytic disorders, hyperglycemia and refeeding), and gastrointestinal complications (regurgitation, vomiting, diarrhea, constipation, intestinal pneumatosis, and jejunal necrosis).3-5

The use of this route for drug administration may also be part of potential complications if the procedure is not adequately planned. Solid drugs usually cause obstructions, resulting in the need of replacing the tube, which increases the costs and the patients' distress.2 Tablets and pills, due to the type of content (liquid, gelatinous or powder) are at risk of being incorrectly diluted or absorbed by gastrointestinal segments that are nor those intended for such administration.6 It is recommended that the drugs characterized by slow or enteric release or microencapsulated drugs are not pulverized, since this reduces the time of drug absorption and causes higher risk of overdose and poisoning.7-9 Even those sweetened liquid drugs may have a significant osmotic or laxative potential due to the presence of substances such as mannitol and sorbitol.

The use of feeding tubes in long-term care facilities (LTCFs) is frequent due to the weakness of the patients.10,11 However, it is difficult to find in the literature studies that assess the association between drugs and feeding tubes in LTCFs. Searching the keywords: drug, therapy, feeding tubes, nursing homes in the website on June 30 2008, we found a total of 18 articles that mostly focused on discussing hydration, nutrition, bronchoscopic aspiration, demential and terminal states. Only two of these studies analyzed drugs and feeding tubes in LTCFs, but both of them considered costs and did not study the pharmacological aspects.12,13 The same keywords were searched for in the website and we could not find any study about this topic.



To define the prevalence of use of drugs incompatible with the enteral route2,6,14 in patients living in LTCFs and using feeding tubes.



This is a retrospective observational study that analyzed the prescriptions of patients using feeding tubes for longer than 48 hours in LTCFs. The study was conducted at Hospital Geriátrico e de Convalescentes Dom Pedro II of Irmandade da Santa Casa de São Paulo, since this LTCF has 508 beds divided among the wards according to the level of physical or mental dependence. Based on the estimate that between 20 and 10% of the patients were using feeding tubes, the minimal sample with potential for statistical analysis was defined as comprising 55 cases (95% confidence interval).

The sample was divided according to sex and age (younger than 60 years old and 60 years old or older), and the active ingredients of the drugs prescribed were compared with the literature on the viability of drugs administered through this route.2,6,8,9,14 We also assessed the forms of presentation (pills, capsules, coated tablets of enteric or extended release drugs) and the possibility of being pulverized. We focused mainly on the forms of presentation including acronyms related to enteric-coated drugs or extended-release drugs, since when these types of drugs are pulverized they undergo a pharmacokinetic intervention performed by the site in the digestive apparatus where the feeding tube is placed, changing its bioavailability and posing the risk of drug poisoning2,8,9 (Table 1). These data constituted the protocol shown in Table 2.2,6,8,9,14

In order to test if there were statistically significant differences, the Fisher's exact test was used regarding proportions and the Student's T test was used regarding means. Values lower than 5% were considered to be statistically significant.

The present study is part of the project no. 061/08 approved by the Ethics Research Committee of Irmandade da Santa Casa de Misericórdia de São Paulo.



We found that 57 patients were using feeding tubes (11.2% of the total number of beds). Their mean age was 65.6 ± 16.0 years old, and 32 of them were women and 25 were men. Those aged younger than 60 years were: 5 women (Group A) and 15 men (Group B) and those aged older than or 60 years were: 27 women (Group C) and 10 men (Group D) (p < 0.001).

Mean of drugs administered through enteral route was 5.6 ± 2.2; of this, 5.2 ± 2.2 were in Group A, 5.7 ± 2.3 were in Group B, 5.7 ± 2.4 were in Group C, and 5.2 ± 2.0 were in Group D (p > 0.05). Items included in the prescriptions were as follows: 316 items divided into 64 drugs, with 129 items (40.8% of the total) and 23 drugs (35.4%) inadequate for this route (p > 0.05 between the groups).

Mean number of inappropriate drugs administered through the enteral route: 2.2 ± 1.5; of this, 1.8 ± 1.9 were in Group A, 2.2 ± 1.6 were in Group B, 2.2 ± 1.7 were in Group C, and 2.3 ± 0.7 were in Group D (p > 0.05). The most often prescribed inappropriate drugs were: lactulose, captopril, phenytoin, ranitidine, omeprazole, complex B, folic acid, tramadol, bromopride, and nifedipine. The alternative forms of presentation were found in 15 (65.2%) of the 23 inappropriate drugs for this route. The list of the inappropriate drugs most often prescribed and their alternative presentations (when there was any) are shown in Table 3.



Forms of drug presentation appropriate for patients with swallowing difficulties may become a challenge in the clinical practice. Even though it ensures a high level of absorption, the parenteral route - intravenous, intramuscular or subcutaneous - poses a potential higher risk of complications, distress, and higher cost. In addition, its use is rare in long-term treatments. Other routes - percutaneous, oral, sublingual, rectal or topic - despite being an alternative method, are limited due to the small number of drugs available for them.

The routine of the care provided to those patients living in LTCFs is usually faced with this situation, in which feeding tubes also become the main administration route of drugs. In such cases, there is often the wrong assumption that the oral and parental routes are similar regarding the pharmacokinetic process and drug bioavailability. Before deciding to keep the same prescription used previously to the passage of the feeding tube, some basic rules should be taken into consideration so that the viability of the drug through this route can be established2,6,8,9,14,15:

- Type of tube - Tubes connected to the stomach usually have larger diameters and are more inexpensive than those connected to the small intestine. Its passage is simpler and the frequency of obstruction is lower than that of the intestinal tubes. Acute cases of dysphagia or digestive disorders or patients who often pull out their tubes are the usual indications for gastric feeding tubes in LTCFs. This type of tube, in addition to being of transient use, is not the preferred administration route for drugs, since it cannot receive diet for at least 30 minutes and needs to be closed after the drugs is administered so that the medication can be released.

- Position of the outlet hole of the tube inside the digestive apparatus - Drugs that act in the stomach, such as antacids, are inappropriate for tubes located in the small intestine areas. Tubes located in the jejunum, on the other hand, increase the bioavailability of the drugs with extensive metabolization during their first passage through the liver, such as beta-blockers, nitrates, tricyclic antidepressives, and opioids.

- Effects of enteral feeding on drugs - Minimum intervals from 15 to 30 minutes without diet before and after receiving medication prevent food-drug interaction, such as, for instance, lactulose, phenytoin, ciprofloxacin, and haloperidol. Therefore, the risk of precipitations, tube obstructions and reduction of serum levels is decreased due to the lower level of absorption of drugs.

- Pulverize only the necessary amount - A procedure that may interfere with the quality of the pharmacological presentation, causing alterations in the serum levels of drugs and increasing the risk of obstructing the tubes. It may also produce aerosols, offering the risk of allergic reactions and teratogenicity to those who handle these drugs. Whenever possible, it is recommended to avoid capsules, pills and forms of presentation that are characterized by slow or enteric release or microencapsulated drugs.

- Use "dispersion methods" whenever possible and do not mix drugs - Choosing easily dissolved drugs reduces the amount of work of those responsible for administrating the drugs. Avoiding mixing drugs decreases the risk of physical, chemical and pharmacological interactions.

- Wash the tube after each administration - Washing the tube before and after drug administration using 20 to 30 ml of distilled water helps to maintain the tube's permeability and reduces the risk of drug adherence to the wall of the feeding tube.

These rules may seem obvious, but they can avoid inefficient and burdensome prescriptions for those responsible for the care of patients using feeding tubes.

The sample of the present study only showed statistical significance related to the larger number of elderly women, which was expected due to the longer female longevity and the correlation between age, dependence, and LTCF.10,11 Considering that the consumption of medications of people living in nursing homes ranges between 3.8 and 11.9,13,16-19 the mean of 5.6 ± 2.2 drugs administered through enteral route we found may be considered to be within the standards of prescriptions in LTCFs. An interesting finding is the high percentage of inappropriate drugs for enteral administration, mainly among those of frequent use, that is, in more than 10% of the sample.

A periodical review of the drugs should be part of the good clinical practice, especially regarding users of feeding tubes and those exposed to multiple drugs at the same time as it happens in LTCFs.



Feeding tubes used as a method to administer drugs has high risk of prescription of inappropriate drugs for people living in nursing homes.



We would like to thank the Center of Publication Support of the School of Medical Sciences of Santa Casa de São Paulo (NAP-SC) for the technical and scientific support regarding the publication of this manuscript.

Conflict of interest: No conflicts of interest declared concerning the publication of this article.



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Artigo recebido: 28/07/08
Aceito para publicação: 08/09/09



Study conducted at Hospital Geriátrico e de Convalescentes Dom Pedro II. Discipline: Basis of Gerontology, Department of Clinical Medicine, School of Medicine, Santa Casa de São Paulo, São Paulo, SP, Brazil
* Correspondência: Hospital Geriátrico e de Convalescentes Dom Pedro II Avenida Guapira, 2674 São Paulo - SP, Brazil CEP: 02265-002 Tel: +55 (11) 2176-1204

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