Losartan
| Evidence Level: L4 | Predicted Indications: 8 |
Table of Contents
Losartan: From Hypertension to Malignant Renovascular Hypertension
One-Sentence Summary
Losartan is an angiotensin II receptor blocker (ARB) widely marketed in South Africa. It is generally used for hypertension, though the registration records supplied do not state the indication. The TxGNN model predicts it may be useful for malignant renovascular hypertension. Support is thin: 0 registered clinical trials and 2 publications (one case report and one preclinical methods paper).
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Hypertension (general pharmacology; the supplied SAHPRA records contain no indication text) |
| Predicted New Indication | Malignant renovascular hypertension |
| TxGNN Prediction Score | 99.73% |
| Evidence Level | L4 |
| South Africa Market Status | Marketed |
| Number of SAHPRA Registrations | 18 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the Evidence Pack. Losartan is an AT1 receptor blocker, which is established pharmacology. Renovascular hypertension is driven by the renin-angiotensin system: a narrowed renal artery reduces kidney perfusion, renin rises, and angiotensin II pushes blood pressure up. Blocking the AT1 receptor is therefore biologically plausible.
The only human evidence is a case report in Takayasu’s arteritis. A patient who had undergone unilateral nephrectomy had malignant hypertension from renal artery stenosis. It was refractory to conventional treatment, and angioplasty was not possible. Enalapril plus losartan improved blood pressure. The abstract excerpt is cut off, so the effect on renal function cannot be confirmed from the data provided. The report also cannot separate losartan’s effect from enalapril’s.
Safety caveat: ARBs can cause acute kidney injury in bilateral renal artery stenosis or in a patient with a solitary kidney. This is the population where renovascular hypertension matters most, so any evaluation would need a safety-first design.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 10667645 | 2000 | Case report | Angiology | Takayasu’s arteritis with malignant hypertension from renal artery stenosis in a unilaterally nephrectomised patient. Enalapril plus losartan improved blood pressure and increased endogenous nitric oxide release. |
| 22294399 | 2009 | Preclinical methods | Current Protocols in Pharmacology | Describes conscious-rat models for measuring antihypertensive activity, including the Goldblatt (renovascular) model. It contains no losartan-specific efficacy data. |
South Africa Market Information
Losartan has 18 SAHPRA registrations. The five main ones are listed below. Indication text was not provided in the registration data.
| Registration Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| Reg. No. 41/7.1.3/0824 | Losartan 50 Strides | Tablet | Not stated in supplied data |
| Reg. No. 41/7.1.3/1075 | Spec-losartan | Tablet | Not stated in supplied data |
| Reg. No. 41/7.1.3/0821 | Ciplazar | Tablet | Not stated in supplied data |
| Reg. No. 41/7.1.3/0497 | Austell losartan | Tablet | Not stated in supplied data |
| Reg. No. 46/7.1.3/0559 | Amzaar 5/50 | Tablet | Not stated in supplied data |
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
In this specific setting, ARBs can cause acute kidney injury in bilateral renal artery stenosis or a solitary kidney (see the caveat above).
Conclusion and Next Steps
Decision: Hold
Rationale: The TxGNN score is very high, and the mechanism is plausible. However, the evidence is one case report combined with an ACE inhibitor and a rodent-model methods paper, with no registered trials. The safety risk in renal artery stenosis is real, and the SAHPRA package insert data have not been reviewed. The other seven predictions (malignant hypertensive renal disease, two pulmonary hypertension categories, Braddock syndrome, Prinzmetal angina, and two rare vascular or small-vessel syndromes) have even less support. They are either preclinical-only (L4) or model prediction only (L5), so they are not recommended for further evaluation now.
To proceed, the following is needed:
- SAHPRA package insert warnings and contraindications, including renal artery stenosis and solitary kidney precautions
- Mechanism of action data confirmed from DrugBank
- A systematic literature search for ARB use in renovascular hypertension, including comparison with ACE inhibitors
- A safety-first study design, with renal function and potassium monitoring, before any prospective evaluation
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.