Drug Analysis: Lisinopril Case Study

Introduction - Lisinopril: An Analysis of the Widely Used Antihypertensive Drug Case Study

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Lisinopril is used for treating patients suffering from hypertension and high blood pressure. The drug is used to treat heart failure and helps to survive after cardiac arrest. The blood pressure can be lowered, and the drug has also been instrumental in treating kidney failures. This drug belongs to the “angiotensin-converting enzyme (ACE) inhibitor” class of drugs. The functional groups of the drug are a “carboxylic acid group” and a “secondary amide group” which is connected to the benzene ring. The drug is prevalently used for heart and kidney diseases; however, side effects of the drug are dizziness, diarrhoea, and dry cough.

Chemistry

The molecular formula for lisinopril is “C21+H31+N3+O5”, and the “empirical formula” is

“C21+H31+N3+O5*2H2O”. It is described as “(S)-1-[N2-(1-carboxy-3-phenyl propyl)-L lysyl]-L-proline dihydrate” having “(2S)-2-methyl-3-sulfanyl propanoyl” as the main functional group (Pubchem. 2022). The “IUPAC name” of the molecule is “(2S)-1-[(2S)-6-amino-2-{[(1S)-1-carboxy-3-phenylpropyl]amino}hexanoyl] pyrrolidine-2-carboxylic acid” which is also known by the trade names “Prinivil”, “Qbrelis”, “Dapril” and “Zestril”.

Figure 1: Structure of Lisinopril

(Source: Self-developed)

The structure of the drug consists of a benzene ring, and 4 chains of carbon-amide are attached to it. It branches in the form of carboxylic acid on one side while a secondary amide on the other side and this side connects to the “rest of the molecule”. The drug branches an amine of 5-carbon having a primary amide attached at end. The branch with the secondary amide has one ketone group attached to the nitrogen within a ring structure of 4-carbon (Castelletto et al. 2021). A carboxylic acid group is present in this carbon ring. The compound exists in a trans-isometric form having an average molecular weight of 405.495 g/mol. The “steric repulsion” between the carboxyl and hydroxyl groups of the drug is lower in this conformation than in the cis form.

Pharmacology

Lisinopril inhibits the activity of ACE in the body, eventually reducing the level of plasma angiotensin II. The level of aldosterone is also reduced, which increases the activity of plasma renin. The blood pressure is gradually reduced in hypertensive patients due to this without adverse effects on the heart rate and cardiovascular reflexes (Rashid et al. 2020). Lisinopril ceases the degradation of the vasodilator Bradykinin (Bk) after being signalled by AT-II. The inhibition of ACE leads to the stoppage of angiotensin II synthesis, and hence the blood pressure is lowered. An increase ratio of "vasodilating angiotensin I” to “vasoconstricting angiotensin II” helps to prevent the development of Bk. The absorption of the drug takes place at a dosage of 0.2 mg/kg, and the absorption process starts within 6 hours of ingestion. The distribution of the rug does not affect the serum proteins; rather, the drug gets eliminated in an unchanged form.

The primary reaction of the body to the drug is that myocyte hypertrophy is prevented, followed by the proliferation of vascular cells of smooth muscles. The absorption of the drug is rarely affected by food since it is almost 60% bioavailable orally and reaches Cmax at 6 hours with 58ng/ml (Ederer et al. 2018). The distribution volume of the drug is 124L, and the route of elimination is only urine. However, the clearance increases with renal function and the mean value are 121 ml/min in an adult. Lisinopril is not known to undergo metabolism since it is entirely excreted in an unchanged form. The effective half-life of the drug is approximately 12.6 hours indicating that it takes almost 12 hours for half of the drug to wear off from the body. The effects of the drug are demonstrated within an hour of ingestion, but the peak time of reaction is within 6 hours (Pubchem. 2022). However, the dosage needs to be more than 20mg, and the overall effects are demonstrated within two weeks.

Clinical uses

Lisinopril is either administered alone or with a combination of other drugs in the treatment of high blood pressure. The usual administration process of the drug is oral and in a single dose, taken only once a day. Doctors recommended the drug be ingested at the same time each day, and there is a limited reaction to the food. Primarily, the patients who are treated with the drug include adults with high blood pressure and also children above the age of 6 years (Pubchem. 2022). Besides blood pressure reduction, the drug is also used in the treatment of hypertension along with other drugs. However, the drug is recommended to be avoided by patients who develop an allergy towards it. Also, people suffering from angioedema and the ones who are allergic to ACE inhibitors, in general, are advised to avoid the medication. Despite the varying applications, the drug might not be effective in every case of heightened blood pressure or hypertension.

The dosage recommended for adults is 10 mg, with an initial dosage of 5 mg in patients who are taking diuretics. The dosage might be increased gradually based on the effectiveness, and there are no other existing routes other than oral administration. The side effects of lisinopril include dry cough, headache, illness, diarrhoea, blurred vision and skin rash (Guglin et al. 2019). Cough and dizziness are the most common side effects of the drug, based on which the dosage might be changed. People taking the drug on a daily basis due to high blood pressure tend to experience kidney problems and fainting symptoms as common side effects. In either case, the precautions suggested by clinicians include monitoring the levels of serum potassium and blood urea. Also, it is prescribed that patients under the medication of drugs like diuretics and anti-inflammatory drugs like ibuprofen must avoid lisinopril. Besides, it is advisable to withdraw the drug in case of prolonged hypotension.

Conclusion

Lisinopril is a universal drug that is administered in patients having high blood pressure and hypotension. Considering the huge benefits of the drug in mitigating adverse health conditions, its universal availability is anticipated. However, the dosage route, amount, and side effects are to be considered prior to administration.

Reference

• Castelletto, V., Seitsonen, J., Ruokolainen, J., Barnett, S.A., Sandu, C. and Hamley, I.W., 2021. Self-assembly of angiotensin-converting enzyme inhibitors captopril and lisinopril and their crystal structures.Langmuir,37(30), pp.9170-9178.
• Ederer, K.A., Jin, K., Bouslog, S., Wang, L., Gorman, G.S., Rowe, G.C., Abadir, P., Raftery, D., Moellering, D., Promislow, D. and Jumbo-Lucioni, P., 2018. Age-and genotype-specific effects of the angiotensin-converting enzyme inhibitor lisinopril on mitochondrial and metabolic parameters in Drosophila melanogaster.International journal of molecular sciences,19(11), p.3351.
• Guglin, M., Krischer, J., Tamura, R., Fink, A., Bello-Matricaria, L., McCaskill-Stevens, W. and Munster, P.N., 2019. Randomized trial of lisinopril versus carvedilol to prevent trastuzumab cardiotoxicity in patients with breast cancer.Journal of the American College of Cardiology,73(22), pp.2859-2868.
• Pubchem. (2022). Lisinopril. Available at: https://pubchem.ncbi.nlm.nih.gov/compound/Lisinopril [Accessed on 12 October 2022]
• Rashid, M., Sarfraz, M., Arafat, M., Hussain, A., Abbas, N., Sadiq, M.W., Rasool, M.F. and Bukhari, N.I., 2020. Prediction of lisinopril pediatric dose from the reference adult dose by employing a physiologically based pharmacokinetic model.BMC Pharmacology and Toxicology,21(1), pp.1-14.